luci_deploy: Enable loading "index.yaml" directly.

deploytool/api/deploy/component.proto

Index: deploytool/api/deploy/component.proto
diff --git a/deploytool/api/deploy/component.proto b/deploytool/api/deploy/component.proto
index febb007d2f668714ddc4d092ee649290cf0de50a..12e119bf4da27d94acc6b3d53a6578e320ce6387 100644
--- a/deploytool/api/deploy/component.proto
+++ b/deploytool/api/deploy/component.proto
@@ -220,6 +220,19 @@ message AppEngineModule {
    * Resource paths may include deployment parameters.
    */
   repeated string resource_path = 23;
+
+  /**
+   * The source-relative path to an "index.yaml" file that can be imported.
+   *
+   * This is specifically useful since GAE development instances are capable
+   * of generating their own index data after observing module behavior. A user
+   * may want to use this behavior directly ratehr rather than translate it
+   * ininto an AppEngineResources protobuf.
+   *
+   * If this is not empty, an "index.yaml" file will be loaded from this path
+   * and appended to any other defined indexes.
+   */
+  string index_yaml_path = 24;
 }
 
 /**