The only thing we have so far is the Wiki on GitHub: https://github.com/strawberrymusicplayer/strawberry/wiki
If someone wants to help with this it would be appreciated.
I was thinking of a MediaWiki site (https://www.mediawiki.org/wiki/MediaWiki) and perhaps a YouTube channel that can also help spread the word and get more active contributors and funding.
I can create the Wiki and the channel if someone volunteers to help with it.
If someone is interested in helping with it, contact me and we can discuss it.
Strawberry is a community based project with limited funding. You can become a GitHub sponsor to help fund the project.

The last release we have for Xenial is 0.5.5 still available on https://github.com/strawberrymusicplayer/strawberry/releases
It's not possible to use a newer version without upgrading Qt and sqlite3 to newer versions.
To use a newer version you need to compile from source and upgrade Qt and sqlite3, maybe those are available through PPA's.