Update changelog

Author: halfalicious

CHANGELOG.md

@@ -11,5 +11,6 @@
 - Fixed: [#5502](https://github.com/ethereum/aleth/pull/5502) Fix Discovery terminating prematurely because of race condition.
 - Fixed: [#5452](https://github.com/ethereum/aleth/pull/5452) Correctly handle Discovery messages when the peer changes public key.
 - Fixed: [#5519](https://github.com/ethereum/aleth/pull/5519) Correctly handle Discovery messages with known public key but unknown endpoint.
+- Added: [#5526](https://github.com/ethereum/aleth/pull/5526) Improved logging when loading chain config json containing syntax error.
 
 [1.6.0]: https://github.com/ethereum/aleth/compare/v1.6.0-alpha.1...master