Require documentation for EvenPodsSpread feature

Author: Tim Bannister

keps/sig-scheduling/20190221-pod-topology-spread.md

@@ -439,6 +439,10 @@ Beta:
   This is particularly for some extended usage such as Cluster Autoscaler.
 - [ ] Add necessary end-to-end tests.
 
+GA:
+
+- [ ] Ensure feature documentation is clear and complete.
+
 ## Alternatives
 
 - mixin new fields into `pod.spec.affinity` to act as a"sub feature" of Affinity