add pr link on CHANGELOG.md

Signed-off-by: channel-dante <[email protected]>

CHANGELOG.md

@@ -39,7 +39,7 @@ This section is for maintaining a changelog for all breaking changes for the cli
 - Added support for icu_collation_keyword type ([#725](https://github.com/opensearch-project/opensearch-java/pull/725))
 - Added support for flat_object field property ([#735](https://github.com/opensearch-project/opensearch-java/pull/735))
 - Added toQuery method in Query and QueryVariant ([#760](https://github.com/opensearch-project/opensearch-java/pull/760)
-- Added toBuilder method to all request model in core package & _types.query_dsl package
+- Added toBuilder method to all request model in core package & _types.query_dsl package ([#766](https://github.com/opensearch-project/opensearch-java/pull/766)
 
 ### Dependencies
 
@@ -256,4 +256,4 @@ This section is for maintaining a changelog for all breaking changes for the cli
 [2.5.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.4.0...v2.5.0
 [2.4.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.3.0...v2.4.0
 [2.3.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.2.0...v2.3.0
-[2.2.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.1.0...v2.2.0
+[2.2.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.1.0...v2.2.0