Add a brief mention of the warning flag name updates associated with the
C++11 standard.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@145284 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/ReleaseNotes.html b/docs/ReleaseNotes.html
index 8a61c8e..636d3e3 100644
--- a/docs/ReleaseNotes.html
+++ b/docs/ReleaseNotes.html
@@ -211,6 +211,9 @@
   <li>A full set of <a href="http://clang.llvm.org/docs/LanguageExtensions.html#checking_type_traits">type traits</a>,
   sufficient to support C++11 standard libraries</li>
 </ul>
+All warning and language selection flags which previously accepted
+<code>c++0x</code> now accept <code>c++11</code>. The old <code>c++0x</code>
+form remains as an alias.
 
 <!-- = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = -->
 <h3 id="objcchanges">Objective-C Language Changes in Clang</h3>