Improve quality of React.DOM deprecation warning comment

Author: nhunzaker

scripts/fiber/tests-passing.txt

@@ -40,6 +40,7 @@ src/addons/__tests__/ReactComponentWithPureRenderMixin-test.js
 
 src/addons/__tests__/ReactDOMFactories-test.js
 * allow factories to be called without warnings
+* warns once when accessing React.DOM methods
 
 src/addons/__tests__/ReactFragment-test.js
 * warns for numeric keys on objects as children

src/isomorphic/React.js

@@ -91,9 +91,9 @@ var React = {
 };
 
 if (__DEV__) {
-  // React.DOM factories are deprecated, set up a Proxy to listen for
-  // accesses to this namespace and alert users to switch to the
-  // associated addon.
+  // React.DOM factories are deprecated. Set up a Proxy to listen for
+  // accesses to the React.DOM namespace and alert users to switch to
+  // the `react-addons-dom-factories` package.
   if (typeof Proxy === 'function') {
     var hasWarnedOfFactories = false;
 
@@ -102,8 +102,8 @@ if (__DEV__) {
         if (!hasWarnedOfFactories) {
           warning(
             false,
-            'Accessing React.DOM factories (like `React.DOM.%s`) is deprecated ' +
-            'and will be removed in the future. Please use the ' +
+            'Accessing factories like React.DOM.%s has been deprecated ' +
+            'and will be removed in the future. Use the ' +
             'react-addons-dom-factories package instead.',
             name
           );