Add graduation criteria for alpha

Author: gjkim42

keps/sig-network/2595-expanded-dns-config/README.md

@@ -15,6 +15,7 @@
 - [Design Details](#design-details)
   - [Test Plan](#test-plan)
   - [Graduation Criteria](#graduation-criteria)
+    - [Alpha](#alpha)
     - [Alpha -> Beta Graduation](#alpha---beta-graduation)
     - [Beta -> GA Graduation](#beta---ga-graduation)
   - [Upgrade / Downgrade Strategy](#upgrade--downgrade-strategy)
@@ -129,6 +130,11 @@ DNS configuration
 
 ### Graduation Criteria
 
+#### Alpha
+
+- Implement the feature
+- Add appropriate unit tests
+
 #### Alpha -> Beta Graduation
 
 - Address feedback from alpha