doc: buserver manpage fixes

 - Add missing -ubikbuffers

 - Remove -enable_peer_stats and -enable_process_stats; we don't
   actually accept these options

 - Fix synopsis formatting, so option arguments are on the same line
   as the option name

 - Fix the -noauth documentation. The current text is referring to the
   client-side -noauth option, but this is actually the server-side
   -noauth option, which is very different.

Change-Id: I11e557e54a8539627ae7bb79cb7af3e8fbc77d25
Reviewed-on: http://gerrit.openafs.org/10389
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>