No need to edit database.yml for standard Postgres

Postgres running on localhost should recognize the `git` system user
used by GitLab so there is no need to set/change database passwords.

doc/install/installation.md

@@ -232,20 +232,21 @@ Make sure to edit both `gitlab.yml` and `unicorn.rb` to match your setup.
 
 ## Configure GitLab DB settings
 
-    # PostgreSQL
+    # PostgreSQL only:
     sudo -u git cp config/database.yml.postgresql config/database.yml
 
-    # Make sure to update username/password in config/database.yml.
+    # MySQL only:
+    sudo -u git cp config/database.yml.mysql config/database.yml
+
+    # MySQL and non-standard PostgreSQL only:
+    # Update username/password in config/database.yml.
     # You only need to adapt the production settings (first part).
     # If you followed the database guide then please do as follows:
     # Change 'secure password' with the value you have given to $password
     # You can keep the double quotes around the password
     sudo -u git -H editor config/database.yml
 
-    or
-    # Mysql
-    sudo -u git cp config/database.yml.mysql config/database.yml
-
+    # PostgreSQL and MySQL:
     # Make config/database.yml readable to git only
     sudo -u git -H chmod o-rwx config/database.yml