Add command line to install only office server

Guides/nextcloud.md

@@ -104,3 +104,13 @@ Refresh Nextcloud cache :
 ```
 sudo nextcloud.occ files:scan --path="/jovian/files/Music"
 ```
+
+## Apps
+
+### Collabora online
+
+Install via CLI with :
+
+```
+sudo -u www-data php -d memory_limit=512M nextcloud.occ app:install richdocumentscode
+```