add symlin(1)

add symlin(1)

SCCS-vsn: usr.bin/chflags/chflags.1 5.3
SCCS-vsn: usr.sbin/chown/chown.8 6.9
SCCS-vsn: usr.sbin/chown/chgrp.1 6.9
SCCS-vsn: bin/chmod/chmod.1 6.17
SCCS-vsn: bin/cp/cp.1 6.20
SCCS-vsn: usr.bin/du/du.1 6.17
SCCS-vsn: usr.bin/find/find.1 6.32
SCCS-vsn: bin/ls/ls.1 6.24
SCCS-vsn: bin/mv/mv.1 6.10
SCCS-vsn: bin/rm/rm.1 6.10
SCCS-vsn: old/tar/tar.1 6.13