doc: fs examine no longer requires read rights on the volume root vnode

doc: fs examine no longer requires read rights on the volume root vnode

Update the man page to reflect the current access rights required for fs
examine.  Historically, fs examine required read access on the root
vnode of the volume housing the directory or file being examined.  This
access check was relaxed in commit d2d591caf2c9b4cf2ebae708cc9b4c8b78ca5a5a,
since the information returned by the file server is already available
anonymously by other means.

Reviewed-on: https://gerrit.openafs.org/12223
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit f99c1ec32bb6e8d31ac517173ff7502dbd85aa05)

Change-Id: I580d1e0cab7f823ac1932f99066495cef9e2410a
Reviewed-on: https://gerrit.openafs.org/12224
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>