add missing "react" namespace to "react/forbid-prop-types"

Author: rutsky

docs/rules/forbid-prop-types.md

@@ -44,7 +44,7 @@ class Component extends React.Component {
 
 ```js
 ...
-"forbid-prop-types": [<enabled>, { "forbid": [<string>] }]
+"react/forbid-prop-types": [<enabled>, { "forbid": [<string>] }]
 ...
 ```