NEWS: Add entry for #412

Signed-off-by: Tamás Kosztyu <[email protected]>

news/feature-412.md

@@ -0,0 +1,15 @@
+grpc: Added service account option for grpc destinations.
+
+Example usage:
+```
+destination {
+    google-pubsub-grpc(
+        project("test")
+        topic("test")
+        auth(service-account(key ("path_to_service_account_key.json")))
+    );
+};
+```
+
+Note: It seems like gRPC sets the audience and scope options
+based on the gRPC service name.