Add 2.2 release note (#450)

* Add 2.2 release note

Signed-off-by: Angie Zhang <langelzh@amazon.com>

* Add 2.2 release note

Signed-off-by: Angie Zhang <langelzh@amazon.com>
(cherry picked from commit 85b9bc4)

Author: Angie-Zhang

release-notes/opensearch-index-management.release-notes-2.2.0.0.md

@@ -0,0 +1,13 @@
+## Version 2.2.0.0 2022-08-05
+
+Compatible with OpenSearch 2.2.0
+
+### Features
+* Ability to count the number of documents from source index ([#439](https://github.com/opensearch-project/index-management/pull/439)) and ([#3985](https://github.com/opensearch-project/OpenSearch/pull/3985))
+
+### Enhancements
+* Support mustache scripting of rollup.target_index field ([#435](https://github.com/opensearch-project/index-management/pull/435))
+* Support searching multiple rollup indices with same mapping ([#440](https://github.com/opensearch-project/index-management/pull/440))
+
+### Maintenance
+* version upgrade to 2.2.0 ([#446](https://github.com/opensearch-project/index-management/pull/446))