Make the note regarding special props in proptypes shorter

content/warnings/special-props.md

@@ -8,15 +8,4 @@ Most props on a JSX element are passed on to the component, however, there are t
 
 For instance, attempting to access `this.props.key` from a component (eg. the render function) is not defined. If you need to access the same value within the child component, you should pass it as a different prop (ex: `<ListItemWrapper key={result.id} id={result.id} />`). While this may seem redundant, it's important to separate app logic from reconciling hints.
 
-> Note:
->
-> There is no need to validate special props using [PropTypes typechecking](https://reactjs.org/docs/typechecking-with-proptypes.html#proptypes).
->
-> By defining `key` or `ref` PropTypes, React will try to access them during props validation phase in the development build.
-> 
-> ```js
-> ListItemWrapper.propTypes = {
->   id: PropTypes.string,
->   key: PropTypes.string // WARNING
-> }
-> ```
+__Note:__ You will also see this warning if you define `key` or `ref` PropTypes (using [PropTypes typechecking](https://reactjs.org/docs/typechecking-with-proptypes.html#proptypes)).