Add "Community Edition" to the version info on the help page

If the version information was hidden because the user was not an admin,
the "GitLab" text looked lonely. This also brings us more in line with
EE which shows "Enterprise Edition".

app/views/help/index.html.haml

 %div
   %h1
     GitLab
+    Community Edition
     - if current_user && current_user.admin?
       %span= Gitlab::VERSION
       %small= Gitlab::REVISION