diff --git a/app/index.yaml b/app/index.yaml
index 6536212..36e4583 100644
--- a/app/index.yaml
+++ b/app/index.yaml
@@ -1,2 +1,8 @@
 indexes:
 # AUTOGENERATED
+
+# This index.yaml is automatically updated whenever the Cloud Datastore
+# emulator detects that a new type of query is run. If you want to manage the
+# index.yaml file manually, remove the "# AUTOGENERATED" marker line above.
+# If you want to manage some indexes manually, move them above the marker line.
+