update changelog with 21.7.1 download link (#2543)

* update changelog post 21.7.1 release

Signed-off-by: garyschulte <garyschulte@gmail.com>
Co-authored-by: Danno Ferrin <danno.ferrin@shemnon.com>

CHANGELOG.md

@@ -1,11 +1,22 @@
 # Changelog
 
+## 21.7.2
+### Additions and Improvements
+
+### Bug Fixes
+
+### Early Access Features
+
 ## 21.7.1
 
 ### Additions and Improvements
 - `priv_call` now uses NO_TRACING OperationTracer implementation which improves memory usage [\#2482](https://github.com/hyperledger/besu/pull/2482)
 - Ping and Pong messages now support ENR encoding as scalars or bytes [\#2512](https://github.com/hyperledger/besu/pull/2512)
 
+### Download Link
+https://hyperledger.jfrog.io/artifactory/besu-binaries/besu/21.7.1/besu-21.7.1.zip \
+sha256sum 83fc44e39a710a95d8b6cbbbf04010dea76122bafcc633a993cd15304905a402
+
 ## 21.7.0
 
 ### Additions and Improvements