Configuration paragraph added in gogs guide

Guides/gogs.md

@@ -52,6 +52,12 @@ Find the script to start gogs programmatically in `Install/Templates/startgogs`
 
 And add the line : `@reboot /home/gituser/gogs/startgogs`
 
+### Configure Gogs
+
+When you start Gogs for the first time, Gogs shows a landing page when you can configure your installation.
+
+Then, if you want to tweak your installation, you can do so by modifying the file `custom/conf/app.ini`. For example, you can disable registration by modifying this line to `DISABLE_REGISTRATION   = true`. Then restart the server to reload configuration changes.
+
 ## Use ssh
 
 ### Add ssh key