Add changelog item

Author: gumb0

CHANGELOG.md

@@ -3,9 +3,9 @@
 ## [1.7.0] - Unreleased
 
 - Added: [#5537](https://github.com/ethereum/aleth/pull/5537) Creating Ethereum Node Record (ENR) at program start.
+- Added: [#5557](https://github.com/ethereum/aleth/pull/5557) Improved debug logging of full sync.
 - Changed: [#5559](https://github.com/ethereum/aleth/pull/5559) Update peer validation error messages.
 
-
 ## [1.6.0] - Unreleased
 
 - Added: [#5485](https://github.com/ethereum/aleth/pull/5485) aleth-bootnode now by default connects to official Ethereum bootnodes. This can be disabled with `--no-bootstrap` flag.