Document and remove some scary warnings from repository hosting

Summary: Fixes T2230. This isn't a total walk in the park to configure, but should work for early adopters now.

Test Plan: Read documentation, browsed UI.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2230

Differential Revision: https://secure.phabricator.com/D7634

scripts/ssh/ssh-exec.php

@@ -100,6 +100,7 @@ try {
 
   $err = $workflow->execute($original_args);
 
+
   $metrics_channel->flush();
   $error_channel->flush();
 } catch (Exception $ex) {