Merge pull request #14570 from ahrtr/changelog_rules

Update changelog readme to add rules on how to add changelog items

CHANGELOG/README.md

@@ -1,4 +1,6 @@
-# Production recommendation
+# Change logs
+
+## Production recommendation
 
 The minimum recommended etcd versions to run in **production** are v3.4.8+ and v3.5.4+. Refer to the [versioning policy](https://etcd.io/docs/v3.5/op-guide/versioning/) for more details.
 
@@ -9,3 +11,11 @@ If etcd process is killed, occasionally some committed transactions are not refl
 Recommendation is to upgrade to v3.5.4+.
 
 If you have encountered data corruption, please follow instructions on https://etcd.io/docs/v3.5/op-guide/data_corruption/.
+
+## Change log rules
+1. Each patch release only includes changes against previous patch release.
+For example, the change log of v3.5.5 should only include items which are new to v3.5.4.
+2. For the first release (e.g. 3.4.0, 3.5.0, 3.6.0, 4.0.0 etc.) for each minor or major 
+version, it only includes changes which are new to the first release of previous minor
+or major version. For example, v3.5.0 should only include items which are new to v3.4.0,
+and v3.6.0 should only include items which are new to v3.5.0.