Add release note for RSA CA changes

Signed-off-by: Matthew Sykes <sykesmat@us.ibm.com>

release_notes/v2.3.0.md

@@ -23,6 +23,15 @@ If adding an organization MSP and a Raft consenter in the same configuration upd
 with error "consensus metadata update for channel config update is invalid" "certificate signed by unknown authority".
 This fix adds logic to verify consenters based on the updated set of organization MSP root CAs.
 
+**FAB-18308: Restore support for MSPs that contain RSA certificate authorities**
+
+While Fabric has never supported RSA for transaction signatures or validation,
+certificate authorities included in MSP definitions could be associated with
+RSA keys. This ability was inadvertently removed during the development of
+release 2.0 and prevented migration of some networks to a 2.x version. With
+these changes, version 2.x components will no longer panic when attempting to
+initialize MSPs that include CA certificates associated with RSA keys.
+
 **peer and orderer PKCS#11 - Always Finalize the PKCS#11 FindObject Operation**
 
 In certain error paths, a PKCS#11 session was not finalized, leaving the session