chore: Add missing items to changelog (#2440)

Add items for SIGHUP database reload and performance improvements.

CHANGELOG.md

@@ -28,6 +28,13 @@ Canonical reference for changes, improvements, and bugfixes for Boundary.
   This allows a worker to reconnect to controllers if the full set of
   controllers has been changed over at the same time, without having to restart
   the worker. ([PR](https://github.com/hashicorp/boundary/pull/2417))
+* Database URL reloading on `SIGHUP`: Controllers will now re-read the database
+    url value from the configuration file when given a SIGHUP. This is
+    particularly useful for allowing database credentials to rotate and
+    signaling the controller to use the new credentials without the need for a
+    restart. ([PR](https://github.com/hashicorp/boundary/pull/2422))
+* Additional improvements to response time for listing sessions and targets
+    ([PR](https://github.com/hashicorp/boundary/pull/2342)).
 
 ### Bug Fixes