message: docs: correct a package of AggregatedDiscoveryService
diff: @@ -528,7 +528,7 @@ in :repo:`this
  <api/XDS_PROTOCOL.md#aggregated-discovery-services-ads>`
  document. The gRPC endpoint is:
  -.. http:post:: /envoy.api.v2.AggregatedDiscoveryService/StreamAggregatedResources
  +.. http:post:: /envoy.service.discovery.v2.AggregatedDiscoveryService/StreamAggregatedResources
  See :repo:`discovery.proto
  <api/envoy/api/v2/discovery.proto>`
  