doc: Add aklog_dynamic_auth manpage

doc: Add aklog_dynamic_auth manpage

Add a manpage for the aklog_dynamic_auth LAM module.

Reviewed-on: http://gerrit.openafs.org/4485
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 24ddd06a0dc19ad7c0b2a2847d41a5ea69665b15)

Change-Id: Ib5f7463b75ee8d58ecc6b725f629fd7600c64792
Reviewed-on: http://gerrit.openafs.org/6297
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>