Update getstorybook instructions for SB4 release (gatsbyjs#9854)

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docs/docs/visual-testing-with-storybook.md

@@ -17,14 +17,16 @@ To set up Storybook you need to install dependencies and do some custom configur
 npm install -g @storybook/cli
 ```
 
-Once the CLI is installed, the next step is to run the `getstorybook` command that is now available from the root directory of your Gatsby project.
+Once the CLI is installed, the next step is to run the `sb init` command that is now available from the root directory of your Gatsby project.
 
 ```sh
 cd my-awesome-gatsby-project
-getstorybook
+sb init
 ```
 
-The `getstorybook` command will then bootstrap the basic config necessary to run Storybook for a React project. However, since this is for a Gatsby project, you need to update the default Storybook configuration a bit so that you don't get errors when trying to use Gatsby specific components inside of the stories.
+> Note that if you're running a recent version of `npm` (5.2.0+) you can run the following single command instead: `npx -p @storybook/cli sb init`, which is the recommended method by Storybook. This doesn't install the CLI on your machine, thereby ensuring you're always running the latest version of the CLI.
+
+The `sb init` command boostraps the basic config necessary to run Storybook for a React project. However, since this is for a Gatsby project, you need to update the default Storybook configuration a bit so that you don't get errors when trying to use Gatsby specific components inside of the stories.
 
 To update your Storybook config open `.storybook/config.js` and add the following before the `configure` method at the bottom of the file.
 

yarn.lock

@@ -11584,6 +11584,13 @@ jws@^3.1.4, jws@^3.1.5:
     jwa "^1.1.5"
     safe-buffer "^5.0.1"
 
+"katex@>=0.10.0 <1.0.0":
+  version "0.10.0"
+  resolved "https://registry.yarnpkg.com/katex/-/katex-0.10.0.tgz#da562e5d0d5cc3aa602e27af8a9b8710bfbce765"
+  integrity sha512-/WRvx+L1eVBrLwX7QzKU1dQuaGnE7E8hDvx3VWfZh9HbMiCfsKWJNnYZ0S8ZMDAfAyDSofdyXIrH/hujF1fYXg==
+  dependencies:
+    commander "^2.16.0"
+
 kebab-case@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/kebab-case/-/kebab-case-1.0.0.tgz#3f9e4990adcad0c686c0e701f7645868f75f91eb"