finalise release changelog and notes (#8987)

CHANGELOG.md

@@ -34,6 +34,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 # Changelog
 
+## [v0.42.3](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.42.3) - 2021-03-24
+
+This release fixes a security vulnerability identified in x/bank.
+
 ## [v0.42.2](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.42.2) - 2021-03-19
 
 ### Improvements

RELEASE_NOTES.md

@@ -1,22 +1,3 @@
-# Cosmos SDK v0.42.2 "Stargate" Release Notes
+# Cosmos SDK v0.42.3 "Stargate" Release Notes
 
-This maintenance release includes various bugfixes and performance improvements, and it does not introduce any breaking changes.
-
-See the [Cosmos SDK v0.42.2 milestone](https://github.com/cosmos/cosmos-sdk/milestone/41?closed=1) on our issue tracker for further details.
-
-### Keyring UX improvement
-
-A number of macOS [users have reported](https://github.com/cosmos/cosmos-sdk/issues/8809) that their operating system's `keychain` prompt them for password to unlock the
-keyring when using the `os` backend before executing any action. This release includes a small fix that automatically
-adjusts applications keyring trust so that users are prompted for password only once when the keyring is unlocked.
-
-### Tx search results support for order-by
-
-Although the Tendermint Core's RPC `tx_search` endpoint has been supporting an order-by parameter for quite some time now,
-the Cosmos SDK did not respect the order-by parameter and incorrectly set the requests order-by to "" (null).
-This releases introduces [the relevant order-by parameter support](https://github.com/cosmos/cosmos-sdk/issues/8686) when searching through Txs.
-
-### Multisig accounts and v0.40 genesis files migration
-
-This release includes a bug fix for [a v0.39 to v0.42 migration issue](https://github.com/cosmos/cosmos-sdk/issues/8776) affecting genesis files that contain
-multisig accounts.
+This release fixes a security vulnerability identified in x/bank.