Merge branch 'patch-20' into 'master'

improve basic details on inspecting NFS mounts

See merge request gitlab-org/gitlab-ce!18734

doc/administration/high_availability/nfs.md

 # NFS
 You can view information and options set for each of the mounted NFS file
-systems by running `sudo nfsstat -m`.
+systems by running `nfsstat -m` and `cat /etc/fstab`.
 ## NFS Server features