Fix a couple of minor signals2 documentation issues.

[SVN r51669]

libs/libraries.htm

@@ -425,6 +425,8 @@ how to download, build, and install the libraries.</p>
 
     <li><a href="signals/index.html">signals</a> - managed signals &amp;
          slots callback implementation, from Doug Gregor.</li>
+    <li><a href="signals2/index.html">signals2</a> - managed signals &amp;
+         slots callback implementation (thread-safe version 2), from Frank Mori Hess.</li>
 
     <li><a href="utility/utility.htm#result_of">result_of</a> - determines the type of a function call expression.</li>
 </ul>

libs/signals2

@@ -1 +1 @@
-Subproject commit cab89ec6a6b30a6ca2781e399271e07ce0068667
+Subproject commit c9bb9ec451b4e6b16c5285592c0d37e722379404