I've gotten some guidelines from RMS about Mailman documentation. I'm wondering if it would be useful for me to create a small working group mailing list for those of you who would like to collaborate on documentation? We can continue to use the mailman-developers list if you prefer.
Documentation should be in Texinfo format, although it is okay to write it in some other format, if what we release is the Texinfo. Please see the GNU Texinfo manual for style guides. RMS sent me the proper assignment forms for both the main manual contributors and for those who donate smaller changes. Let me know and I will send them to you.