The current version of NickelMenu works without any issues that I've noticed on my Libra Colour. The doc file copied into the /.adds/nm directory is the documentation file. And no, there are no downloadable files though there is a thread called
Best of NickelMenu? which has several people's config files in it. The problem is that most of us are very different in what we use NickelMenu for and so our choice of commands vary greatly.
AFAIK, 0.5.4 is still the latest available from the P Gaskin's GitHub
Nickelmenu site.
If you install a KOReader nightly newer than -22 (2024-May-09), it should work on your Libra Colour. See
Index of /download/nightly/ for the download links.
I've placed my current NM config in the spoiler/code tags below: