[guide] [react] add note about forbid-prop-types rule

Author: Rahil Vora

react/README.md

@@ -28,6 +28,7 @@ This style guide is mostly based on the standards that are currently prevalent i
     - However, multiple [Stateless, or Pure, Components](https://facebook.github.io/react/docs/reusable-components.html#stateless-functions) are allowed per file. eslint: [`react/no-multi-comp`](https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/no-multi-comp.md#ignorestateless).
   - Always use JSX syntax.
   - Do not use `React.createElement` unless you’re initializing the app from a file that is not JSX.
+  - [`react/forbid-prod-types`](https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/forbid-prop-types.md) will allow `arrays` and `objects` only if it is explicitly noted what `array` and `object` contains, using `arrayOf`, `objectOf`, or `shape`.
 
 ## Class vs `React.createClass` vs stateless