docs: stop generating schema doc for 'bridges' root

apps/emqx_bridge/src/schema/emqx_bridge_schema.erl

@@ -172,7 +172,7 @@ namespace() -> "bridge".
 tags() ->
     [<<"Bridge">>].
 
-roots() -> [{bridges, ?HOCON(?R_REF(bridges), #{importance => ?IMPORTANCE_LOW})}].
+roots() -> [{bridges, ?HOCON(?R_REF(bridges), #{importance => ?IMPORTANCE_HIDDEN})}].
 
 fields(bridges) ->
     [

apps/emqx_dashboard/src/emqx_dashboard_schema_api.erl

@@ -44,6 +44,7 @@ paths() ->
     ["/schemas/:name"].
 
 %% This is a rather hidden API, so we don't need to add translations for the description.
+%% TODO(5.7): delete 'bridges'
 schema("/schemas/:name") ->
     Schemas = [hotconf, bridges, actions, connectors],
     #{