Merge branch 'rs-troubleshooting' into 'master'

Add Troubleshooting section to 8.0 docs

[ci skip]

See merge request !1416

doc/install/installation.md

@@ -518,3 +518,13 @@ You also need to change the corresponding options (e.g. `ssh_user`, `ssh_host`,
 ### Additional Markup Styles
 
 Apart from the always supported markdown style there are other rich text files that GitLab can display. But you might have to install a dependency to do so. Please see the [github-markup gem readme](https://github.com/gitlabhq/markup#markups) for more information.
+
+## Troubleshooting
+
+### "You appear to have cloned an empty repository."
+
+If you see this message when attempting to clone a repository hosted by GitLab,
+this is likely due to an outdated Nginx or Apache configuration, or a missing or
+misconfigured `gitlab-git-http-server` instance. Double-check that you've
+[installed Go](#3-go), [installed gitlab-git-http-server](#install-gitlab-git-http-server),
+and correctly [configured Nginx](#site-configuration).

doc/update/7.14-to-8.0.md

@@ -192,3 +192,13 @@ sudo -u git -H bundle exec rake gitlab:backup:restore RAILS_ENV=production
 ```
 
 If you have more than one backup `*.tar` file(s) please add `BACKUP=timestamp_of_backup` to the command above.
+
+## Troubleshooting
+
+### "You appear to have cloned an empty repository."
+
+If you see this message when attempting to clone a repository hosted by GitLab,
+this is likely due to an outdated Nginx or Apache configuration, or a missing or
+misconfigured `gitlab-git-http-server` instance. Double-check that you correctly
+completed [Step 5](#5-install-gitlab-git-http-server) to install the daemon and
+[Step 8](#new-nginx-configuration) to reconfigure Nginx.