Required permission:
- Create custom module (to add an add-on)
- Delete custom module (to remove one)

- Add: install the add-on. A dialog asks for its Name (the label in the left menu) and Address (the last part of its page address), both filled in for you.
- Configure: on an installed add-on, change its name or address.
- Remove: uninstall it after confirming. Its menu entry and permission are removed.
