Added a link to the list of all tz database time zones

site/docs/configuration.md

@@ -91,8 +91,9 @@ class="flag">flags</code> (specified on the command-line) that control them.
             environment variable, which Ruby uses to handle time and date
             creation and manipulation. Any entry from the
             <a href="http://en.wikipedia.org/wiki/Tz_database">IANA Time Zone
-            Database</a> is valid, e.g. <code>America/New_York</code>. The default
-            is the local time zone, as set by your operating system.
+            Database</a> is valid, e.g. <code>America/New_York</code>. A list of all 
+            available values can be found <a href="http://en.wikipedia.org/wiki/List_of_tz_database_time_zones">
+            here</a>. The default is the local time zone, as set by your operating system.
         </p>
       </td>
       <td class='align-center'>
@@ -380,4 +381,4 @@ In addition to the defaults mentioned above, you can also turn on recognition of
 For example, in your `_config.yml`:
 
     kramdown:
-      input: GFM
+      input: GFM