Support - fix some docs on ssh hosting

Summary: Fixes T6169 by using the new nav element on the existing troubleshooting hint the user missed. Fixes T6173 by implementing the user's suggestion.

Test Plan: Looked at docs and they looked good.

Reviewers: epriestley, chad

Reviewed By: chad

Subscribers: fas, epriestley, Korvin

Maniphest Tasks: T6169, T6173

Differential Revision: https://secure.phabricator.com/D10548