MFC r306611:
Amend history to mention predecessor originated from 386BSD[1] & current implementation from NetBSD[2].
Reword history since the utility was renamed once more in FreeBSD 5.0.
Separate out author & historical information regarding character code conversion.
Add AUTHORS section.

[1] https://groups.google.com/forum/#!search/mount_pcfs.c/comp.unix.bsd/9qhH0v1tZm0/inlPnXZj_2sJ
[2] http://cvsweb.netbsd.org/bsdweb.cgi/src/sbin/mount_msdos/mount_msdos.c?rev=1.6&content-type=text/x-cvsweb-markup

PR: 212536
Approved by: bcr (mentor)
Differential Revision: https://reviews.freebsd.org/D8105