Align "default SSH config" warning text with docs

Follow-up to 86d52920

doc/ssh/README.md

@@ -359,7 +359,7 @@ Git user has default SSH configuration? ... no
   sudo mv /var/lib/git/.ssh/id_rsa ~/gitlab-check-backup-1504540051
   sudo mv /var/lib/git/.ssh/id_rsa.pub ~/gitlab-check-backup-1504540051
   For more information see:
-  doc/ssh/README.md in section "SSH on the GitLab server"
+  [Overriding SSH settings on the GitLab server](#overriding-ssh-settings-on-the-gitlab-server)
   Please fix the error above and rerun the checks.
 ```
 

lib/system_check/app/git_user_default_ssh_config_check.rb

@@ -31,7 +31,7 @@ module SystemCheck
         end
 
         try_fixing_it("mkdir #{backup_dir}", *instructions)
-        for_more_information('doc/ssh/README.md in section "SSH on the GitLab server"')
+        for_more_information('doc/ssh/README.md in section "Overriding SSH settings on the GitLab server"')
         fix_and_rerun
       end