F-Droid listing TODO list

[r4sas]

I'll try to add application to F-Droid, but to add it to the catalog we need to do the following:

• Add yggdrasil-go as submodule to use specified commit at release, not master trunk. I think better to add it as submodule to path app/libs/yggdrasil-go
• Add fastlane structure with application information, screenshots and changelogs
• Write metadata for building application in fdroidserver (done, but changes needed; see step 1)