Replace :SERVER with :example.com

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/configuring-playbook-bridge-appservice-discord.md

@@ -81,5 +81,5 @@ There's the Discord bridge's guide for [setting privileges on bridge managed roo
 
 ```sh
 docker exec -it matrix-appservice-discord \
-/bin/sh -c 'cp /cfg/registration.yaml /tmp/discord-registration.yaml && cd /tmp && node /build/tools/adminme.js -c /cfg/config.yaml -m "!ROOM_ID:SERVER" -u "@USER:SERVER" -p 100'
+/bin/sh -c 'cp /cfg/registration.yaml /tmp/discord-registration.yaml && cd /tmp && node /build/tools/adminme.js -c /cfg/config.yaml -m "!ROOM_ID:example.com" -u "@USER:example.com" -p 100'
 ```