update release notes

RELEASENOTES.md

@@ -6,6 +6,55 @@ This document contains the release notes for `rippled`, the reference server imp
 
 Have new ideas? Need help with setting up your node? [Please open an issue here](https://github.com/xrplf/rippled/issues/new/choose).
 
+# Version 2.3.1
+
+Version 2.3.1 of `rippled`, the reference server implementation of the XRP Ledger protocol, is now available. This release fixes an erroneous high fee penalty that peers can be charged for sending older transactions.
+
+[Sign Up for Future Release Announcements](https://groups.google.com/g/ripple-server)
+
+<!-- BREAK -->
+
+## Action Required
+
+If you run an XRP Ledger validator, upgrade to version 2.3.1 as soon as possible to ensure stable and uninterrupted network behavior.
+
+## Changelog
+
+### Amendments and New Features
+
+- None
+
+### Bug Fixes and Performance Improvements
+
+- Change the charged fee for sending older transactions from feeInvalidSignature to feeUnwantedData. [#5243](https://github.com/XRPLF/rippled/pull/5243)
+
+### Docs and Build System
+
+- None
+
+### GitHub
+
+The public source code repository for `rippled` is hosted on GitHub at <https://github.com/XRPLF/rippled>.
+
+We welcome all contributions and invite everyone to join the community of XRP Ledger developers to help build the Internet of Value.
+
+
+## Credits
+
+The following people contributed directly to this release:
+
+Ed Hennis <ed@ripple.com>
+JoelKatz <DavidJoelSchwartz@GMail.com>
+Sophia Xie <106177003+sophiax851@users.noreply.github.com>
+Valentin Balaschenko <13349202+vlntb@users.noreply.github.com>
+
+
+Bug Bounties and Responsible Disclosures:
+
+We welcome reviews of the `rippled` code and urge researchers to responsibly disclose any issues they may find.
+
+To report a bug, please send a detailed report to: <bugs@xrpl.org>
+
 # Version 2.3.0
 
 Version 2.3.0 of `rippled`, the reference server implementation of the XRP Ledger protocol, is now available. This release includes 8 new amendments, including Multi-Purpose Tokens, Credentials, Clawback support for AMMs, and the ability to make offers as part of minting NFTs. Additionally, this release includes important fixes for stability, so server operators are encouraged to upgrade as soon as possible.