Merge PR cosmos#4967: Split Breaking Changes into Specific Subsections

CHANGELOG.md

@@ -26,7 +26,9 @@ Types of changes (Stanzas):
 "Improvements" for changes in existing functionality.
 "Deprecated" for soon-to-be removed features.
 "Bug Fixes" for any bug fixes.
-"Breaking" for breaking API changes.
+"Client Breaking" for breaking CLI commands and REST routes used by end-users.
+"API Breaking" for breaking exported APIs used by developers building on SDK.
+"State Machine Breaking" for any changes that result in a different AppState given same genesisState and txList.
 
 Ref: https://keepachangelog.com/en/1.0.0/
 -->
@@ -35,13 +37,18 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
-### Breaking Changes
+
+### API Breaking Changes
 
 * (modules) [\#4665](https://github.com/cosmos/cosmos-sdk/issues/4665) Refactored `x/gov` module structure and dev-UX:
   * Prepare for module spec integration
   * Update gov keys to use big endian encoding instead of little endian
+
+### Client Breaking Changes
+
 * (rest) [\#4783](https://github.com/cosmos/cosmos-sdk/issues/4783) The balance field in the DelegationResponse type is now sdk.Coin instead of sdk.Int
 
+
 ### Features
 
 * (cli) [\#4973](https://github.com/cosmos/cosmos-sdk/pull/4973) Enable application CPU profiling