documentation updates

[Doug Morris]

I've created a subdirectory "docs" in the nmh sources and moved most
of the files that were In the top level into it. The sources were
getting pretty messy. Anyone working with the cvs versions should
probablly do

  cvs update -d

to bring your local copy in sync. 

I've also added a MAILING-LISTS file to the docs directory explaining
the lists and the mail archives, and updated the FAQ. 

-Doug