Fix changelog post release (#1424)

Signed-off-by: Thomas Farr <[email protected]>

Author: Xtansia

Diff for: CHANGELOG.md

@@ -6,10 +6,6 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Bumps `org.eclipse.parsson:parsson` from 1.1.6 to 1.1.7
 - Bumps `org.hamcrest:hamcrest` from 2.2 to 3.0
 - Bumps `com.github.jk1.dependency-license-report` from 2.8 to 2.9
-- Bumps `org.apache.httpcomponents.client5:httpclient5` from 5.4 to 5.4.2 ([#1401](https://github.com/opensearch-project/opensearch-java/pull/1401))
-- Bumps `org.apache.httpcomponents.core5:httpcore5` from 5.3 to 5.3.3 ([#1383](https://github.com/opensearch-project/opensearch-java/pull/1383), [#1402](https://github.com/opensearch-project/opensearch-java/pull/1402))
-- Bump `org.junit:junit-bom` from 5.11.3 to 5.11.4 ([#1367](https://github.com/opensearch-project/opensearch-java/pull/1367))
-- Bump `org.owasp.dependencycheck` from 11.1.1 to 12.0.2 ([#1381](https://github.com/opensearch-project/opensearch-java/pull/1381), [#1393](https://github.com/opensearch-project/opensearch-java/pull/1393), [#1399](https://github.com/opensearch-project/opensearch-java/pull/1399), [#1404](https://github.com/opensearch-project/opensearch-java/pull/1404))
 - Bump `commons-logging:commons-logging` from 1.3.4 to 1.3.5 ([#1418](https://github.com/opensearch-project/opensearch-java/pull/1418))
 
 This section is for maintaining a changelog for all breaking changes for the client that cannot be released in the 2.x line. All other non-breaking changes should be added to [Unreleased 2.x] section.
@@ -58,10 +54,22 @@ This section is for maintaining a changelog for all breaking changes for the cli
 ### Removed
 
 ### Fixed
-- Fixed serialization of `time_zone` field in `CompositeDateHistogramAggregationSource` ([#1362](https://github.com/opensearch-project/opensearch-java/pull/1362))
 
 ### Security
 
+## [2.20.0] - 02/04/2025
+### Added
+- Added support for `KnnQuery`'s `expand_nested_docs`, `method_parameters` and `rescore` properties ([#1407](https://github.com/opensearch-project/opensearch-java/pull/1407))
+
+### Dependencies
+- Bump `org.junit:junit-bom` from 5.11.3 to 5.11.4 ([#1367](https://github.com/opensearch-project/opensearch-java/pull/1367))
+- Bumps `org.apache.httpcomponents.client5:httpclient5` from 5.4 to 5.4.2 ([#1401](https://github.com/opensearch-project/opensearch-java/pull/1401))
+- Bumps `org.apache.httpcomponents.core5:httpcore5` from 5.3 to 5.3.3 ([#1383](https://github.com/opensearch-project/opensearch-java/pull/1383), [#1402](https://github.com/opensearch-project/opensearch-java/pull/1402))
+- Bump `org.owasp.dependencycheck` from 11.1.1 to 12.0.2 ([#1381](https://github.com/opensearch-project/opensearch-java/pull/1381), [#1393](https://github.com/opensearch-project/opensearch-java/pull/1393), [#1399](https://github.com/opensearch-project/opensearch-java/pull/1399))
+
+### Fixed
+- Fixed serialization of `time_zone` field in `CompositeDateHistogramAggregationSource` ([#1362](https://github.com/opensearch-project/opensearch-java/pull/1362))
+
 ## [2.19.0] - 12/12/2024
 ### Added
 - Added support for `IcuCollationKeywordProperty`'s `country`, `language` and `variant` properties ([#1321](https://github.com/opensearch-project/opensearch-java/pull/1321))
@@ -603,7 +611,8 @@ This section is for maintaining a changelog for all breaking changes for the cli
 ### Security
 
 [Unreleased 3.0]: https://github.com/opensearch-project/opensearch-java/compare/2.x...HEAD
-[Unreleased 2.x]: https://github.com/opensearch-project/opensearch-java/compare/v2.19.0...2.x
+[Unreleased 2.x]: https://github.com/opensearch-project/opensearch-java/compare/v2.20.0...2.x
+[2.20.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.19.0...v2.20.0
 [2.19.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.18.0...v2.19.0
 [2.18.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.17.0...v2.18.0
 [2.17.0]: https://github.com/opensearch-project/opensearch-java/compare/v2.16.0...v2.17.0