[static] Add release notes for 0.4.23 (#3014)

Signed-off-by: Nicu Reut <nicu.reut@digitalasset.com>

Author: nicu-da

docs/src/release_notes.rst

@@ -8,8 +8,8 @@
 Release Notes
 =============
 
-Upcoming
---------
+0.4.23
+------
 
   - Daml
 
@@ -24,6 +24,18 @@ Upcoming
       both for featured and unfeatured apps.
 
 
+  - Performance improvements
+
+    - Scan
+
+        - Cache open rounds with a default TTL of 30s. This should reduce load when rounds change and lots of clients try to read the open rounds. `View PR 2860. <https://github.com/hyperledger-labs/splice/pull/2860>`_
+
+        - Reduce database load when the connection to the mediator verdict ingestion is restarted. `View PR 2861. <https://github.com/hyperledger-labs/splice/pull/2861>`_
+
+  - Deployment
+
+    - Increased the resource allocation for most apps, double check any changes if you override the default resources. `View PR 2972. <https://github.com/hyperledger-labs/splice/pull/2972>`_
+
 0.4.22
 ------