[Doc] Replace codesandbox links by stackblitz for issue reproduction

.github/CONTRIBUTING.md

@@ -16,7 +16,7 @@ For code issues please include:
 * React-admin version
 * React version
 * Browser version
-* A code example or link to a repo, gist or running site. (hint: fork [this sandbox](https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple) to create a reproducible version of your bug)
+* A code example or link to a repo, gist or running site. (hint: fork [this sandbox](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple) to create a reproducible version of your bug)
 
 For visual or layout problems, images or animated gifs can help explain your issue.
 It's even better with a live reproduction test case.

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -21,11 +21,9 @@ about: Something isn't working as expected. Please tell us!
 **Related code:**
 <!-- If you are able to illustrate the bug or feature request with an example, please provide a sample application via one of the following means: -->
 
-* Preferably, a CodeSandbox forked from 
-  - https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple (v4)
-  - https://codesandbox.io/s/github/marmelab/react-admin/tree/3.x/examples/simple (v3)
-* A StackBlitz forked from 
+* Preferably, a sandbox forked from 
   - https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple (v4)
+  - https://codesandbox.io/s/github/marmelab/react-admin/tree/3.x/examples/simple (v3)
 * A link to a GitHub repo with the minimal codebase to reproduce the issue
 
 

README.md

@@ -130,11 +130,11 @@ React-admin is designed as a library of loosely coupled React components and hoo
 
 There are several examples inside the `examples` folder:
 
-* `simple` ([CodeSandbox](https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple), [StackBlitz](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple?file=src%2Findex.tsx)): a simple blog with posts, comments and users that we use for our e2e tests.
+* `simple` ([StackBlitz](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple?file=src%2Findex.tsx)): a simple blog with posts, comments and users that we use for our e2e tests.
 * `e-commerce`: ([demo](https://marmelab.com/react-admin-demo/), [source](https://github.com/marmelab/react-admin/tree/master/examples/demo)) A fictional poster shop admin, serving as the official react-admin demo.
 * `CRM`: ([demo](https://marmelab.com/react-admin-crm/), [source](https://github.com/marmelab/react-admin/tree/master/examples/crm)) A customer relationship management application
 * `helpdesk`: ([demo](https://marmelab.com/react-admin-helpdesk/), [source](https://github.com/marmelab/react-admin-helpdesk)) A ticketing application with realtime locks and notifications
-* `tutorial` ([CodeSandbox](https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/tutorial)): the application built while following the [tutorial](https://marmelab.com/react-admin/Tutorial.html).
+* `tutorial` ([Stackblitz](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/tutorial)): the application built while following the [tutorial](https://marmelab.com/react-admin/Tutorial.html).
 
 You can run those example applications by calling:
 
@@ -199,7 +199,7 @@ You can use Gitpod (an open source, online VS Code-like IDE) for working on issu
 
 ### Testing Your Changes In The Example Apps
 
-When developing, most of the time we use the **simple example** to do visual check. It's the same application that we use in CodeSandbox to reproduce errors (see https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple). The source is located under `examples/simple/`. Call `make run` to launch that example on port 8080 (http://localhost:8080). This command includes a `watch` on the react-admin source, so any of the changes you make to the react-admin packages triggers a live update of the simple example in your browser. 
+When developing, most of the time we use the **simple example** to do visual check. It's the same application that we use in Stackblitz to reproduce errors (see https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple). The source is located under `examples/simple/`. Call `make run` to launch that example on port 8080 (http://localhost:8080). This command includes a `watch` on the react-admin source, so any of the changes you make to the react-admin packages triggers a live update of the simple example in your browser. 
 
 However, the simple example is sometimes too limited. You can use the **demo example** (the source for https://marmelab.com/react-admin-demo/), which is more complete. The source is located under `examples/demo/`. Call `make run-demo` to launch the demo example with a REST dataProvider, or `make run-graphql-demo` to run it with a GraphQL dataProvider. Unfortunately, due to the fact that we use Create React App for this demo, these commands don't watch the changes made in the packages. You'll have to rebuild the react-admin packages after a change (using `make build`, or the more targeted `make build-ra-core`, `make build-ra-ui-materialui`, etc.) to see the effect in the demo app.
 

docs/Demos.md

@@ -88,8 +88,8 @@ A simple application with posts, comments and users that we use for our e2e test
 
 ![Blog demo](./img/blog_demo.png)
 
-* Demo: [https://iuxnw.sse.codesandbox.io/](https://iuxnw.sse.codesandbox.io/)
-* Source code: [https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple](https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple)
+* Demo: [https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple)
+* Source code: [https://github.com/marmelab/react-admin/tree/master/examples/simple](https://github.com/marmelab/react-admin/tree/master/examples/simple)
 
 ## Broadcom Layer 7 API Hub
 

examples/simple/README.md

@@ -1,6 +1,6 @@
 # React-admin Simple Example
 
-This is the application we use for our end-to-end tests, and for reproducing bugs via CodeSandbox.
+This is the application we use for our end-to-end tests, and for reproducing bugs via [Stackblitz](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple).
 
 ## How to run
 

packages/react-admin/README.md

@@ -139,8 +139,8 @@ React-admin is designed as a library of loosely coupled React components built o
 
 There are several examples inside the `examples` folder:
 
-* `simple` ([CodeSandbox](https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple)): a simple application with posts, comments and users that we use for our e2e tests.
-* `tutorial` ([CodeSandbox](https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/tutorial)): the application built while following the tutorial.
+* `simple` ([Stackblitz](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple)): a simple application with posts, comments and users that we use for our e2e tests.
+* `tutorial` ([Stackblitz](https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/tutorial)): the application built while following the tutorial.
 * `demo`: ([Live](https://marmelab.com/react-admin-demo/)) A fictional poster shop admin, serving as the official react-admin demo.
 
 You can run those example applications by calling:
@@ -205,7 +205,7 @@ You can use Gitpod(An Online Open Source VS Code like IDE which is free for Open
 
 ### Testing Your Changes In The Example Apps
 
-When developing, most of the time we use the **simple example** to do visual check. It's the same application that we use in CodeSandbox to reproduce errors (see https://codesandbox.io/s/github/marmelab/react-admin/tree/master/examples/simple). The source is located under `examples/simple/`. Call `make run` to launch that example on port 8080 (http://localhost:8080). This command includes a `watch` on the react-admin source, so any of the changes you make to the react-admin packages triggers a live update of the simple example in your browser. 
+When developing, most of the time we use the **simple example** to do visual check. It's the same application that we use in Stackblitz to reproduce errors (see https://stackblitz.com/github/marmelab/react-admin/tree/master/examples/simple). The source is located under `examples/simple/`. Call `make run` to launch that example on port 8080 (http://localhost:8080). This command includes a `watch` on the react-admin source, so any of the changes you make to the react-admin packages triggers a live update of the simple example in your browser. 
 
 However, the simple example is sometimes too limited. You can use the **demo example** (the source for https://marmelab.com/react-admin-demo/), which is more complete. The source is located under `examples/demo/`. Call `make run-demo` to launch the demo example with a REST dataProvider, or `make run-graphql-demo` to run it with a GraphQL dataProvider. Unfortunately, due to the fact that we use Create React App for this demo, these commands don't watch the changes made in the packages. You'll have to rebuild the react-admin packages after a change (using `make build`, or the more targeted `make build-ra-core`, `make build-ra-ui-materialui`, etc) to see the effect in the demo app.