Tweak markdown to fix links and prevent warnings
Some markdown links were not properly formatted, and some square brackets were not encapsulated in backticks, causing bad links and kramdown warnings. This should fix most of them.
$ bundle exec nanoc
Loading site… done
kramdown warning(s) for <Nanoc::CompilationItemRepView item.identifier=/omnibus/docker/README.md name=default>
No link definition for link ID 'starter only' found on line 75
No link definition for link ID 'directory resource: /data/gitlab' found on line 489
kramdown warning(s) for <Nanoc::CompilationItemRepView item.identifier=/omnibus/settings/logs.md name=default>
No link definition for link ID 'svlogd' found on line 41
No link definition for link ID 'svlogd' found on line 41
No link definition for link ID 'svlogd' found on line 41
No link definition for link ID 'svlogd' found on line 41
kramdown warning(s) for <Nanoc::CompilationItemRepView item.identifier=/omnibus/settings/redis.md name=default>
No link definition for link ID 'setting up a redis-only server' found on line 113
No link definition for link ID '' found on line 113
kramdown warning(s) for <Nanoc::CompilationItemRepView item.identifier=/omnibus/common_installation_problems/README.md name=default>
No link definition for link ID '' found on line 54
No link definition for link ID 'gitlab.rb.template' found on line 80
No link definition for link ID '' found on line 80
kramdown warning(s) for <Nanoc::CompilationItemRepView item.identifier=/omnibus/gitlab-mattermost/README.md name=default>
No link definition for link ID ''db2_backup_created'' found on line 402
No link definition for link ID ''db2_team_name'' found on line 403