doc: Add glfs_fini known issue to release notes 3.5

Adds the glfs_fini issue as reported in
http://lists.gnu.org/archive/html/gluster-devel/2014-04/msg00179.html
to the release notes.

Change-Id: I91965e80939b69205d12e8c35f0c17ccd3a9ccc2
BUG: 1091340
Signed-off-by: Deepak C Shetty <deepakcs@redhat.com>
Reviewed-on: http://review.gluster.org/7559
Reviewed-by: Humble Devassy Chirammal <humble.devassy@gmail.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>