doc: Fix Solaris 11 kernel module path

For Solaris 11, the module goes in drv, not fs.

Reviewed-on: http://gerrit.openafs.org/8152
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Ken Dreyer <ktdreyer@ktdreyer.com>
(cherry picked from commit a7278eb5620507cd70086582cf539b4024b46194)

Change-Id: Idb5f864132f436f9a6cc619d1c672c9ceec3ff67
Reviewed-on: http://gerrit.openafs.org/9566
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>