doc: -afsdb uses SRV records

doc: -afsdb uses SRV records

afsd's -afsdb option now uses DNS SRV records (RFC 5864). Update the manpages
to reflect this.

Reviewed-on: http://gerrit.openafs.org/4670
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 884d0b058cea4ad6c9338fc7842ea0c619cb263d)

Change-Id: Ibcdb7c0564d9ac56fa9e50123950e7f758761111
Reviewed-on: http://gerrit.openafs.org/4701
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>