sshpeer: add a configurable hint for the ssh error message Adding a possibility to configure error hint to be shown in the case of problems with SSH. Example of such hint can be "Please see http://company/internalwiki/ssh.html". Test Plan: - Ran hg pull with broken link and verified the output has no hint by default: ``` pulling from ssh://brokenrepository.com//repo remote: ssh: Could not resolve hostname brokenrepository.com: Name or service not known abort: no suitable response from remote hg! ``` - Run hg pull --config ui.ssherrorhint="Please see http://company/internalwiki/ssh.html": ``` pulling from ssh://brokenrepository.com//repo remote: ssh: Could not resolve hostname brokenrepository.com: Name or service not known abort: no suitable response from remote hg! (Please see http://company/internalwiki/ssh.html) ``` Differential Revision: https://phab.mercurial-scm.org/D1431