[wwwdocs] Update libstdc++ release notes in gcc-6/changes.html

[Jonathan Wakely <jwakely at redhat dot com>]

Committed to cvs.

Index: htdocs/gcc-6/changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-6/changes.html,v
retrieving revision 1.42
diff -u -r1.42 changes.html
--- htdocs/gcc-6/changes.html	15 Nov 2015 08:01:27 -0000	1.42
+++ htdocs/gcc-6/changes.html	17 Nov 2015 10:49:56 -0000
@@ -117,14 +117,28 @@
         <li>non-member functions <code>std::size</code>,
             <code>std::empty</code>, and <code>std::data</code> for
             accessing containers and arrays;</li>
+        <li><code>std::invoke</code>;</li>
         <li><code>std::shared_mutex</code>;</li>
         <li><code>std::void_t</code> and <code>std::bool_constant</code>
-            utilities. </li>
+            metaprogramming utilities. </li>
       </ul>
+      Thanks to Ville Voutilainen for contributing many of the C++17 features.
     </li>
     <li>An experimental implementation of the File System TS.</li>
     <li>Experimental support for most features of the second version of the
-        Library Fundamentals TS.</li>
+        Library Fundamentals TS, including polymorphic memory resources and
+        array support in <code>shared_ptr</code>, thanks to Fan You.</li>
+    <li>Some assertions checked by Debug Mode can now also be enabled by
+        <code>_GLIBCXX_ASSERTIONS</code>. The subset of checks enabled by
+        the new macro have less run-time overhead than the full
+        <code>_GLIBCXX_DEBUG</code> checks and and don't affect the library
+        ABI, so can be enabled per-translation unit.
+    </li>
+    <li>Timed mutex types are supported on more targets, including Darwin.
+    </li>
+    <li>Improved <code>std::locale</code> support for DragonFly and FreeBSD,
+        thanks to John Marino and Andreas Tobler.
+    </li>
   </ul>