Update CHANGELOG for 2.5.0 (#1258)

* Upgrade CHANGELOG for 2.5.0

* Minor cleanup

* Add librdkafka features to CHANGELOG.md

* Remove KIPs without code changes

---------

Co-authored-by: Milind L <milindl@users.noreply.github.com>
Co-authored-by: Milind L <miluthra@confluent.io>

CHANGELOG.md

@@ -5,6 +5,16 @@
 This is a feature release.
 
  * Adds an AdminAPI `DeleteRecords()` (#1141, @PratRanj07).
+ * Add support for metadata and ruleSet in the schema registry client, which together support data
+contracts.
+ * Add a new Avro package "avrov2" which uses the Avro hamba library.  The old package "avro" uses
+Avro libraries which are no longer maintained and should not be used in new code.
+ * Move rest service for schema registry client into internal package for use by both the SR client
+and the DEK Registry client.
+ * Add support for CSFLE (client-side field-level encryption) for AWS, Azure, GCP, and HashiCorp
+Vault.  See the encryption examples in the examples directory.
+ * Add support for CEL, CEL_FIELD, and JSONata rules.
+
 
 ## Fixes