Updated CHANGELOG for LL128 support for gfx942 in 7.0 (#1719)

* Updated CHANGELOG for LL128 support for gfx942 in 7.0

Also ported 6.4.2 section

* Removed unnecessary note from 7.0

[ROCm/rccl commit: e73db11819]

projects/rccl/CHANGELOG.md

@@ -31,6 +31,12 @@ Full documentation for RCCL is available at [https://rccl.readthedocs.io](https:
 * Compatibility with NCCL 2.25.1
 * Compatibility with NCCL 2.26.6
 
+## RCCL 2.22.3 for ROCm 6.4.2
+
+### Added
+
+* Added support for the LL128 protocol on gfx942.
+
 ## RCCL 2.22.3 for ROCm 6.4.1
 
 ### Resolved issues