Merge pull request kubernetes#3206 from wojtek-t/update_kep_template

Update KEP template with comment wrt to enablement/disablement tests in PRR section

Author: k8s-ci-robot

keps/NNNN-kep-template/README.md

@@ -444,6 +444,12 @@ The e2e framework does not currently support enabling or disabling feature
 gates. However, unit tests in each component dealing with managing data, created
 with and without the feature, are necessary. At the very least, think about
 conversion tests if API types are being modified.
+
+Additionally, for features that are introducing a new API field, unit tests that
+are exercising the `switch` of feature gate itself (what happens if I disable a
+feature gate after having objects written with the new field) are also critical.
+You can take a look at one potential example of such test in:
+https://github.com/kubernetes/kubernetes/pull/97058/files#diff-7826f7adbc1996a05ab52e3f5f02429e94b68ce6bce0dc534d1be636154fded3R246-R282
 -->
 
 ### Rollout, Upgrade and Rollback Planning