Add the app to F-droid repository

[damascene]

I suggest adding the app to F-droid repository. It's basically about having release tags, creating some metadata folders and updating change log.
I've recently experienced the process and I think it will be useful to have the App available on f-droid.

More information are available here:
https://f-droid.org/en/docs/Submitting_to_F-Droid_Quick_Start_Guide/

If you agree to have it on F-droid I may create some PRs to help with it.