readd commit activity

Author: matthiasdiener

content/help.html

@@ -19,7 +19,7 @@
       <a href="https://charm.readthedocs.io/en/latest/faq/manual.html">[html]</a>
     </li>
     <li>Charm++ Tutorial <a href="https://charm.cs.illinois.edu/tutorial/">[html]</a> </li>
-    <li>Recent Commit Activity <a href="">[html]</a> </li>
+    <li>Recent Commit Activity <a href="https://github.com/UIUC-PPL/charm/commits/master">[html]</a> </li>
     <li>Nightly Regression Tests <a href="https://charm.cs.illinois.edu/autobuild/cur/">[html]</a> </li>
     <li>Manuals
       <ul style="padding-left:20px">