doc: fileserver synopsis typo

doc: fileserver synopsis typo

Fix a fileserver synopsis typo noticed during Derrick's EACK2011
debugging session.

Reviewed-on: http://gerrit.openafs.org/5558
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit f2cba414c1390d5ed46b6c57f5682bfbcf53774e)

Change-Id: I8765cb2e5b3e0c64611a02dd59b4a8f9a2dac5eb
Reviewed-on: http://gerrit.openafs.org/5559
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>