Chore: prepare for 2.5.0 release (#323)

* update changelog

* update changelog

* updated changelog

CHANGELOG.md

@@ -4,12 +4,16 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-## Unreleased
+
+## [2.5.0] - Sep 24, 2021
+
+  - Add new fields (sdkKey, environmentKey, attributes, audiences, events, experimentRules, deliveryRules) to `/config` endpoint ([PR #322](https://github.com/optimizely/agent/pull/322)):  
+
 ## [2.4.0] - March 3, 2021
 ## New Features
-Introduce `/decide` endpoint as a new primary interface for Decide APIs, that is for retrieving feature flag status, configuration and associated experiment decisions for users ([#292](https://github.com/optimizely/agent/pull/292)).   
+- Introduce `/decide` endpoint as a new primary interface for Decide APIs, that is for retrieving feature flag status, configuration and associated experiment decisions for users ([#292](https://github.com/optimizely/agent/pull/292)).   
 
-For details about this Agent release, refer to our documentation page: https://docs.developers.optimizely.com/full-stack/v4.0/docs/optimizely-agent.  
+- For details about this Agent release, refer to our documentation page: https://docs.developers.optimizely.com/full-stack/v4.0/docs/optimizely-agent.  
 Upgrade to use [Go SDK v1.6.1](https://github.com/optimizely/go-sdk/tree/v1.6.1). This adds support for OptimizelyDecision.
 
 ## [2.3.1] - November 17, 2020