This README.md file exists for people browsing on github.
The TeX-Live project on github (https://github.com/TeX-Live) is a mirror of the upstream Subversion repository (https://tug.org/texlive/svn). We use it primarily for automatic building of the sources on several platforms.
The releases built here (https://github.com/TeX-Live/texlive-source/releases) are not usable TeX systems on their own, but bare binary directories. They can be dropped into a TeX Live installation as some bin/newdir and they should work, including resolving the dangling symlinks that are in the bare tarballs.
For reports and other feedback, we prefer using mailing lists: tex-live@tug.org for general bugs and discussion, tex-k@tug.org for bugs and patches for the compiled programs, and so on. All the TL mailing lists: https://tug.org/texlive/lists.html.
However, if you prefer to open issues or submit PRs on github, that's ok. We will see them and will reply as soon as we can.
One common problem: Package bug reports should go to the package maintainer, however they wish to receive reports, not to any general TeX Live list. TL redistributes what is uploaded to CTAN without changes.
For technical information about the source tree here, see the ./README file here, not this README.md.