Add tcp995 (in /rc/bin/service.auth) to listen(8).

Make the service and service.auth tables match the 
distributed scripts: (Move tcp567, tcp110, tcp22 to
service.auth table. Move tcp993 to service table. Delete
tcp566, tcp17008, tcp1723.)

Order both tables by port number. Capitalize/punctuate
descriptions consistently. Make all-caps acronyms .SM.
Make SOURCE section normal.

Did not add any of the  il* scripts in /rc/bin/service*.
Tcp17005 and tcp17006 in /rc/bin/service invoke a
/bin/ocpu that is not in the dist, and so are not
documented.

Changed usage() in /sys/src/cmd/aux/^(listen.c listen1.c)
to match the dist man page.