adding notes to gitlab nginx conf

We want to make users aware that the nginx default config will conflict
with the gitlab default_server conf file.

doc/install/installation.md

@@ -353,6 +353,9 @@ Make sure to edit the config file to match your setup:
 
     # Change YOUR_SERVER_FQDN to the fully-qualified
     # domain name of your host serving GitLab.
+    # If using Ubuntu default nginx install:
+    # either remove the default_server from the listen line
+    # or else rm -f /etc/sites-enabled/default
     sudo editor /etc/nginx/sites-available/gitlab
 
 **Note:** If you want to use HTTPS, replace the `gitlab` Nginx config with `gitlab-ssl`. See [Using HTTPS](#using-https) for HTTPS configuration details.

lib/support/nginx/gitlab

@@ -34,7 +34,11 @@ upstream gitlab {
 
 ## Normal HTTP host
 server {
-  listen 0.0.0.0:80 default_server;
+  
+  listether remove "default_server" from the listen line below, 
+  ## or delete the /etc/nginx/sites-enabled/default file. This will cause gitlab
+  ## to be served if you visit any address that your server responds to, eg.
+  ## the ip address of the server (http://x.x.x.x/)n 0.0.0.0:80 default_server;
   listen [::]:80 default_server;
   server_name YOUR_SERVER_FQDN; ## Replace this with something like gitlab.example.com
   server_tokens off; ## Don't show the nginx version number, a security best practice

lib/support/nginx/gitlab-ssl

@@ -38,6 +38,10 @@ upstream gitlab {
 
 ## Redirects all HTTP traffic to the HTTPS host
 server {
+  ## Either remove "default_server" from the listen line below, 
+  ## or delete the /etc/nginx/sites-enabled/default file. This will cause gitlab
+  ## to be served if you visit any address that your server responds to, eg.
+  ## the ip address of the server (http://x.x.x.x/)
   listen 0.0.0.0:80;
   listen [::]:80 default_server;
   server_name YOUR_SERVER_FQDN; ## Replace this with something like gitlab.example.com