Switch 2.x.x to be released from 2.x branch (#183)

Signed-off-by: Peter Zhu <[email protected]>

Author: peterzhuamazon

README.md

@@ -23,8 +23,9 @@
 A community repository for Ansible Playbook of OpenSearch Project.
 
 ## Version and Branching
-As of now, this ansible-playbook repository maintains 2 branches:
-* _main_ (Version is 2.x.x for both `os_version` and `os_dashboards_version` in `inventories/opensearch/group_vars/all/all.yml`)
+As of now, this ansible-playbook repository maintains these branches:
+* _main_ (Version is 3.x.x for both `os_version` and `os_dashboards_version` in `inventories/opensearch/group_vars/all/all.yml`)
+* _2.x_ (Version is 2.x.x for both `os_version` and `os_dashboards_version` in `inventories/opensearch/group_vars/all/all.yml`)
 * _1.x_ (Version is 1.x.x for both `os_version` and `os_dashboards_version` in `inventories/opensearch/group_vars/all/all.yml`)
 <br>
 
@@ -49,7 +50,7 @@ This ansible playbook supports the following,
 ### Prerequisite
 
 - **Ansible 2.9+**
-- **Java 8**
+- **Java 11**
 
 ### Configure