Request: Add Koel Community App

[YozoraXCII]

I am looking to have Koel added as a community app if possible, It is available from https://github.com/koel/docker.

Worth noting that the base version does not have on-demand scanning, but inotifywait can be set up to facilitate this, as described here: https://docs.koel.dev/watch.html#introduction - not sure if it is possible to include this within the app so that it doesn't require setting up manually.