docs: added per-block root change

CHANGELOG.md

@@ -1,4 +1,4 @@
-## 2022-11-14 v0.13.0
+## 2022-11-15 v0.13.0
 
 Release highlights:
 - A [Waku canary tool](https://github.com/status-im/nwaku/tree/2336522d7f478337237a5a4ec8c5702fb4babc7d/tools#waku-canary-tool) to check if nodes are reachable and what protocols they support.
@@ -33,6 +33,7 @@ Release highlights:
 - Cleaned up compiler warnings on unused imports.
 - Improved exception handling and annotation.
 - [`13/WAKU2-STORE`](https://rfc.vac.dev/spec/13/) no longer enabled by default on nwaku nodes.
+- Merkle tree roots for RLN membership changes now on a per-block basis to allow poorly connected peers to operate within a window of acceptable roots.
 
 ### Fixes