Improve API doc for pool.ha_cluster_stack field

Also set the default to "". This avoids having any cluster-stack specifics in
the datamodel.

Signed-off-by: Rob Hoes <[email protected]>

Author: robhoes

ocaml/idl/datamodel.ml

@@ -6670,7 +6670,7 @@ let pool =
 			; field ~in_oss_since:None ~in_product_since:rel_midnight_ride ~qualifier:DynamicRO ~ty:String ~default_value:(Some (VString "")) "vswitch_controller" "address of the vswitch controller"
 			; field ~in_oss_since:None ~in_product_since:rel_midnight_ride ~qualifier:DynamicRO ~ty:(Map(String, String)) ~default_value:(Some (VMap [])) "restrictions" "Pool-wide restrictions currently in effect"
 			; field ~in_oss_since:None ~in_product_since:rel_boston ~qualifier:DynamicRO ~ty:(Set (Ref _vdi)) "metadata_VDIs" "The set of currently known metadata VDIs for this pool"
-			; field ~in_oss_since:None ~in_product_since:rel_dundee ~qualifier:DynamicRO ~default_value:(Some (VString "xhad")) ~ty:String "ha_cluster_stack" "The ha cluster manager stack"
+			; field ~in_oss_since:None ~in_product_since:rel_dundee ~qualifier:DynamicRO ~default_value:(Some (VString "")) ~ty:String "ha_cluster_stack" "The HA cluster stack that is currently in use. Only valid when HA is enabled."
 
 			] @ (allowed_and_current_operations pool_operations) )
 		()