add how to integrate

describe, how to integrate a pad

docs/configuring-playbook-etherpad.md

@@ -59,3 +59,7 @@ If you wish to disable the Etherpad chat button, you can do it by appending `?sh
 
 If your Etherpad widget fails to load, this might be due to Dimension generating a Pad name so long, the Etherpad app rejects it.
 `$roomId_$padName` can end up being longer than 50 characters. You can avoid having this problem by altering the template so it only contains the three word random identifier `$padName`.
+
+## How to use etherpad
+
+This is how it works in element. It might work similar in other clients: To integrate a standalone etherpad in a room, create your pad, copy the url and send to the room `/addwidget <url>`. You will then find your integrated etherpad within the right sidebar in the `Widgets` section.