Re-add Nginx configuration to 8.0-to-8.1 update guide

doc/update/8.0-to-8.1.md

@@ -109,6 +109,27 @@ There are new configuration options available for [`gitlab.yml`](config/gitlab.y
 git diff origin/8-0-stable:config/gitlab.yml.example origin/8-1-stable:config/gitlab.yml.example
 ```
 
+#### Nginx configuration
+
+View changes between the previous recommended Nginx configuration and the
+current one:
+
+```sh
+# For HTTPS configurations
+git diff origin/8-0-stable:lib/support/nginx/gitlab-ssl origin/8-1-stable:lib/support/nginx/gitlab-ssl
+
+# For HTTP configurations
+git diff origin/8-0-stable:lib/support/nginx/gitlab origin/8-1-stable:lib/support/nginx/gitlab
+```
+
+If you are using Apache instead of NGINX please see the updated [Apache templates].
+Also note that because Apache does not support upstreams behind Unix sockets you
+will need to let gitlab-git-http-server listen on a TCP port. You can do this
+via [/etc/default/gitlab].
+
+[Apache templates]: https://gitlab.com/gitlab-org/gitlab-recipes/tree/master/web-server/apache
+[/etc/default/gitlab]: https://gitlab.com/gitlab-org/gitlab-ce/blob/8-1-stable/lib/support/init.d/gitlab.default.example#L34
+
 ### 8. Start application
 
     sudo service gitlab start