modify changelog for v2 release (#1230)

Author: KonradStaniec

CHANGELOG.md

@@ -37,6 +37,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 ## Unreleased
 
+## v2.0.0
+
 - [#12226](https://github.com/babylonlabs-io/babylon/pull/1191](https://github.com/babylonlabs-io/babylon/pull/1226) chore: Revert goreleaser to use musl
 
 ## v2.0.0-rc.4