Merge pull request #2250 from edx/feanil/update_sandbox_workers-1

Be able to update workers.

playbooks/roles/edx_ansible/templates/update.j2

@@ -12,7 +12,7 @@ IFS=","
             -v        add verbosity to edx_ansible run
             -h        this
 
-    <repo> - must be one of edx-platform, xqueue, cs_comments_service, xserver, ease, edx-ora, configuration, read-only-certificate-code, edx-analytics-data-api
+    <repo> - must be one of edx-platform, edx-workers, xqueue, cs_comments_service, xserver, ease, edx-ora, configuration, read-only-certificate-code, edx-analytics-data-api
     <version> - can be a commit or tag
 
 EO