Also, according to the document you mentioned, people are expected to
know diff, texinfo, and mercurial. I am sure that most Octave users
who would agree to submit their stuff are not used to working with
these tools, so they won't submit their work. Is there a way to get
around this? If so, this should be explained in the above document,
too.
This is the main obstacle to improving documentation, in my opinion.
Maybe it could be possible to have the manual on a wiki, so that
people
can make corrections directly there? I know it would not work, but
starting from this idea, maybe someone more knowledgeable than me on
web
applications could devise something...