Added note about chown when migrating to another server

committer note: changed text slightly...

doc/admin.mkd

@@ -312,6 +312,9 @@ if things are not clear -- you can help me fine tune this document :-)
         mv repositories/gitolite-admin.git $HOME/old-gitolite-admin.git
         find repositories -name gitolite-hooked | xargs rm
 
+    Don't forget to chown repositories if git's UID changed.  Gitolite expects
+    the hosting user to own all the files and directories it manages.
+
   * (workstation, new server) **install** gitolite normally on your new
     server.  Use whatever install method suits you, but you must use the
     **same** name for the admin ("YourName" in the install instructions).  You