Add note in View.js render method that wrapper component is not used.

Summary: Got bitten lately by View.js returning different component based on `__DEV__`

Adding a warning in the render method that should make it cleaner in the future that this method is not actually being used in prod mode.
Closes facebook#4322

Reviewed By: svcscm

Differential Revision: D2691880

Pulled By: vjeux

fb-gh-sync-id: 119672740969a857ab6288b7914d52e8d40a1d95

Libraries/Components/View/View.js

@@ -312,6 +312,10 @@ var View = React.createClass({
   },
 
   render: function() {
+    // WARNING: This method will not be used in production mode as in that mode we
+    // replace wrapper component View with generated native wrapper RCTView. Avoid
+    // adding functionality this component that you'd want to be available in both
+    // dev and prod modes.
     return <RCTView {...this.props} />;
   },
 });