Expanded the mention of the $SIGNATURE environment variable to talk about the three different ways to override "From:" header construction.  Also added mh-tailor(5) to the "SEE ALSO" section.
Expanded the mention of the $SIGNATURE environment variable to talk about the
three different ways to override "From:" header construction.  Also added
mh-tailor(5) to the "SEE ALSO" section.

mcr/nmh,dscho/nmh,mcr/nmh,dscho/nmh,dscho/nmh,dscho/nmh