Update the note on issues link to reflect that it points to github now

Author: jelford

doc/_templates/localtoc.html

@@ -26,7 +26,7 @@ <h3>quicklinks</h3>
 </td></tr><tr><td>
         <a href="{{ pathto('config') }}">config</a>
 </td><td>
-        <a href="https://github.com/tox-dev/tox/issues">issues[bb]</a>
+        <a href="https://github.com/tox-dev/tox/issues">issues[gh]</a>
 </td></tr><tr><td>
         <a href="{{ pathto('support') }}">support</a>
 </td><td>