Migrate the shared file systems documents from the
centralized Admin Guide as outlined in the migration
spec [1].
[1] https://specs.openstack.org/openstack/docs-specs/specs/pike/os-manuals-migration.html
Partial-Bug: #1706181
Needed-By: Ibe3588c3f4560c037cf109058fc357234e70a846
Depends-On: Ieea33262101a1d2459492c1c8aaac5fe042279f6
Depends-On: Ia750cb049c0f53a234ea70ce1f2bbbb7a2aa9454
Change-Id: I7924d94b82e7c8d9716bad7a219fc38c57970773
