Update CHANGELOG.md in prepration for v2.1 (#3319)

CHANGELOG.md

@@ -8,12 +8,14 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 and follows a [Backwards Compatibility Policy](https://docs.solanalabs.com/backwards-compatibility)
 
 Release channels have their own copy of this changelog:
-* [edge - v2.1](#edge-channel)
-* [beta - v2.0](https://github.com/solana-labs/solana/blob/v2.0/CHANGELOG.md)
-* [stable - v1.18](https://github.com/solana-labs/solana/blob/v1.18/CHANGELOG.md)
+* [edge - v2.2](#edge-channel)
+* [beta - v2.1](https://github.com/solana-labs/solana/blob/v2.1/CHANGELOG.md)
+* [stable - v2.0](https://github.com/solana-labs/solana/blob/v2.0/CHANGELOG.md)
 
 <a name="edge-channel"></a>
-## [2.1.0] - Unreleased
+## [2.2.0] - Unreleased
+
+## [2.1.0]
 * Breaking:
   * SDK:
     * `cargo-build-sbf` and `cargo-build-bpf` have been deprecated for two years and have now been definitely removed.