[Api-ref] Add supported protocol "MAPRFS" in doc
Now that the "MAPRFS" has been supported by manila driver,
but this is missing in share.inc docs, this change is to add
it.
@@ -23,6 +23,8 @@ To create a share, specify one of these supported protocols:
- ``CEPHFS``. Ceph File System (CephFS).
+- ``MAPRFS``. MapR File System (MAPRFS).
+
You can also create snapshots of shares. To create a snapshot, you
specify the ID of the share that you want to snapshot.
