Add explanation for adding everything as dependencies to docs (#6082)

* Update available-scripts.md

add the reason for adding packages as dependencies

* Update available-scripts.md

* Update available-scripts.md

* Update available-scripts.md


Co-authored-by: Amy Lam <amy.r.lam@gmail.com>
Co-authored-by: Ian Sutherland <ian@iansutherland.ca>

docusaurus/docs/available-scripts.md

@@ -30,6 +30,10 @@ Your app is ready to be deployed! See the section about [deployment](deployment.
 
 If you aren’t satisfied with the build tool and configuration choices, you can `eject` at any time. This command will remove the single build dependency from your project.
 
-Instead, it will copy all the configuration files and the transitive dependencies (Webpack, Babel, ESLint, etc) right into your project so you have full control over them. All of the commands except `eject` will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
+Instead, it will copy all the configuration files and the transitive dependencies (Webpack, Babel, ESLint, etc.) into your project as dependencies in `package.json`. Technically, the distinction between dependencies and development dependencies is pretty arbitrary for front-end apps that produce static bundles.
+
+In addition, it used to cause problems with some hosting platforms that didn't install development dependencies (and thus weren't able to build the project on the server or test it right before deployment). You are free to rearrange your dependencies in `package.json` as you see fit.
+
+All of the commands except `eject` will still work, but they will point to the copied scripts so you can tweak them. At this point you’re on your own.
 
 You don’t have to ever use `eject`. The curated feature set is suitable for small and middle deployments, and you shouldn’t feel obligated to use this feature. However we understand that this tool wouldn’t be useful if you couldn’t customize it when you are ready for it.