Mention recent C++ API tweaks in CHANGELOG
@@ -53,6 +53,11 @@ and this project adheres to [Semantic Versioning].
[[#442](https://github.com/ethereum/evmc/pull/442)]
- In the Rust bindings make `ExecutionContext` optional within `execute`.
[[#350](https://github.com/ethereum/evmc/pull/350)]
+- A set of small improvements to C++ API
+ [[#445](https://github.com/ethereum/evmc/pull/445),
+ [#449](https://github.com/ethereum/evmc/pull/449),
+ [#451](https://github.com/ethereum/evmc/pull/451)]
+
## [6.3.1] - 2019-08-19
