Fixed missing CHANGELOG notes from ROCm 5.5 through unreleased 6.1 (#1141)

* Update CHANGELOG.md for ROCm release 5.5

(cherry picked from commit 975327be45f2313dc7249f9c54ad90870e833a4a)

* Update CHANGELOG.md for ROCm 5.7.0

(cherry picked from commit ac8db8d8e0853f1783c10e2858f6c3b86e4d27cb)

* Added ROCm 6.0 and 6.1 CHANGELOG notes.

---------

Co-authored-by: gilbertlee-amd <44450918+gilbertlee-amd@users.noreply.github.com>

CHANGELOG.md

@@ -2,7 +2,33 @@
 
 Full documentation for RCCL is available at [https://rccl.readthedocs.io](https://rccl.readthedocs.io)
 
-## Unreleased
+## Unreleased - RCCL 2.18.6 for ROCm 6.1.0
+### Changed
+- Compatibility with NCCL 2.18.6
+### Added
+### Fixed
+### Removed
+
+## RCCL 2.18.3 for ROCm 6.0.0
+### Changed
+- Compatibility with NCCL 2.18.3
+### Added
+### Fixed
+### Removed
+
+## RCCL 2.17.1-1 for ROCm 5.7.0
+### Changed
+- Compatibility with NCCL 2.17.1-1
+- Performance tuning for some collective operations
+### Added
+- Minor improvements to MSCCL codepath
+- NCCL_NCHANNELS_PER_PEER support
+- Improved compilation performance
+- Support for gfx94x
+### Fixed
+- Potential race-condition during ncclSocketClose()
+
+## RCCL 2.16.2 for ROCm 5.6.0
 ### Changed
 - Compatibility with NCCL 2.16.2
 ### Added
@@ -10,7 +36,7 @@ Full documentation for RCCL is available at [https://rccl.readthedocs.io](https:
 - Remove workaround and use indirect function call
 ### Removed
 
-## Unreleased - RCCL 2.15.5 for ROCm 5.5.0
+## RCCL 2.15.5 for ROCm 5.5.0
 ### Changed
 - Compatibility with NCCL 2.15.5
 - Unit test executable renamed to rccl-UnitTests