Add note that most of C++ is not supported.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@53023 91177308-0d34-0410-b5e6-96231b3b80d8

www/cxx_status.html

@@ -20,7 +20,8 @@
 <!--*************************************************************************-->
 
 <p>
-This page tracks the status of C++ support in Clang.</p>
+This page tracks the status of C++ support in Clang.<br>
+Currently most of the C++ features are missing; here you can find features that are at least partially supported in Clang. </p>
 <table width="689" border="1">
   <tr>
     <td width="150"><h3>Feature</h3></td>