docs/67806: Let 5.x users know how to boot into single user mode in cutting-edge.

[Giorgos Keramidas]

Synopsis: Let 5.x users know how to boot into single user mode in cutting-edge.

State-Changed-From-To: feedback->open
State-Changed-By: keramida
State-Changed-When: Thu Jul 8 22:10:33 GMT 2004
State-Changed-Why: 
Doug-Erling explained to me what I was missing.  Put this back into
the pool of open PRs.

http://www.freebsd.org/cgi/query-pr.cgi?pr=67806