docs: move contributing guidelines to CONTRIBUTING.md (#2386)

CONTRIBUTING.md

@@ -0,0 +1,37 @@
+# Contributing to validator.js
+Welcome to validator.js repository!! We appreciate your interest in contributing to this open library and for helping our community grow. 
+
+## How to Contribute
+### Code Contribution
+In general, we follow the "fork-and-pull" Git workflow.
+
+1. [Fork](https://docs.github.com/en/get-started/exploring-projects-on-github/contributing-to-a-project) the repository on GitHub
+2. Clone the project to your local machine
+3. Work on your fork
+    * Make your changes and additions
+        - Most of your changes should be focused on src/ and test/ folders and/or [README.md](https://github.com/validatorjs/validator.js/blob/master/README.md).
+        - Files such as validator.js, validator.min.js and files in lib/ folder are autogenerated when running tests (npm test) and need not to be changed **manually**.
+    * Change or add tests if needed
+    * Run tests and make sure they pass
+    * Add changes to README.md if needed
+4. Commit changes to your own branch
+5. **Make sure** you merge the latest from "upstream" and resolve conflicts if there is any
+6. Repeat step 3(3) above
+7. Push your work back up to your fork
+8. Submit a Pull request so that we can review your changes
+
+#### Run Tests
+Tests are using mocha. To run the tests use:
+
+```sh
+$ npm test
+```
+
+### Financial Contribution
+We welcome financial contributions on our [open collective](https://opencollective.com/validatorjs).
+
+You can opt to become a [backer](https://opencollective.com/validatorjs#backer) or a [sponsor](https://opencollective.com/validatorjs#sponsor) and help our project sustain over time.
+
+Thank you to the people who have already contributed:
+
+<a href="https://github.com/validatorjs/validator.js/graphs/contributors"><img src="https://opencollective.com/validatorjs/contributors.svg?width=890" /></a>

README.md

@@ -72,16 +72,6 @@ CDN
 <script src="https://unpkg.com/validator@latest/validator.min.js"></script>
 ```
 
-## Contributors
-
-[Become a backer](https://opencollective.com/validatorjs#backer)
-
-[Become a sponsor](https://opencollective.com/validatorjs#sponsor)
-
-Thank you to the people who have already contributed:
-
-<a href="https://github.com/validatorjs/validator.js/graphs/contributors"><img src="https://opencollective.com/validatorjs/contributors.svg?width=890" /></a>
-
 ## Validators
 
 Here is a list of the validators currently available.
@@ -202,33 +192,6 @@ XSS sanitization was removed from the library in [2d5d6999](https://github.com/v
 
 For an alternative, have a look at Yahoo's [xss-filters library](https://github.com/yahoo/xss-filters) or at [DOMPurify](https://github.com/cure53/DOMPurify).
 
-## Contributing
-
-In general, we follow the "fork-and-pull" Git workflow.
-
-1. Fork the repo on GitHub
-2. Clone the project to your own machine
-3. Work on your fork
-    1. Make your changes and additions
-        - Most of your changes should be focused on `src/` and `test/` folders and/or `README.md`.
-        - Files such as `validator.js`, `validator.min.js` and files in `lib/` folder are autogenerated when running tests (`npm test`) and need not to be changed **manually**.
-    2. Change or add tests if needed
-    3. Run tests and make sure they pass
-    4. Add changes to README.md if needed
-4. Commit changes to your own branch
-5. **Make sure** you merge the latest from "upstream" and resolve conflicts if there is any
-6. Repeat step 3(3) above
-7. Push your work back up to your fork
-8. Submit a Pull request so that we can review your changes
-
-## Tests
-
-Tests are using mocha, to run the tests use:
-
-```sh
-$ npm test
-```
-
 ## Maintainers
 
 - [chriso](https://github.com/chriso) - **Chris O'Hara** (author)