fix TOC

Signed-off-by: Andrew Sy Kim <andrewsy@google.com>

Author: andrewsykim

keps/sig-node/4742-node-topology-downward-api/README.md

@@ -12,10 +12,10 @@
   - [Risks and Mitigations](#risks-and-mitigations)
 - [Design Details](#design-details)
   - [Test Plan](#test-plan)
-    - [Prerequisite testing updates](#prerequisite-testing-updates)
-    - [Unit tests](#unit-tests)
-    - [Integration tests](#integration-tests)
-    - [e2e tests](#e2e-tests)
+      - [Prerequisite testing updates](#prerequisite-testing-updates)
+      - [Unit tests](#unit-tests)
+      - [Integration tests](#integration-tests)
+      - [e2e tests](#e2e-tests)
   - [Graduation Criteria](#graduation-criteria)
     - [Alpha](#alpha)
     - [Beta](#beta)