JohnWho, - I agree. - As you say, the first line of the current readme.txt file states...
Marine Aquarium 3.0 User's Guide
It is not the sort of typical readme.txt file listing chronological update details etc, it is a user guide. - So lets call it what it is... userguide.txt ?
As I've already said,
"If we call it what it is, (a user guide), then people may be more ready to use it."
I think most people ignore readme.txt files as being just boring. - But 'UserGuide' might just work!