doc/mgr/smb: Fix a typo in options for cluster resource

Custom options to the ceph.smb.cluster resource are expected under
"custom_smb_global_options" and not "custom_smb_share_options".

Signed-off-by: Anoop C S <[email protected]>

Author: anoopcs9

doc/mgr/smb.rst

@@ -360,7 +360,7 @@ custom_dns
 placement
     Optional. A Ceph Orchestration :ref:`placement specifier
     <orchestrator-cli-placement-spec>`.  Defaults to one host if not provided
-custom_smb_share_options
+custom_smb_global_options
     Optional mapping. Specify key-value pairs that will be directly added to
     the global ``smb.conf`` options (or equivalent) of a Samba server.  Do
     *not* use this option unless you are prepared to debug the Samba instances