[Version] Increment to 2.1.1 (#1862)

Increment version from 2.1.0 to 2.1.1 and updated the branch to be 2.1 for
docs for example:
https://opensearch.org/docs/2.1/dashboards/index/

Issue Related:
#1771

Signed-off-by: Kawika Avilla <kavilla414@gmail.com>

package.json

@@ -11,8 +11,8 @@
     "dashboarding"
   ],
   "private": true,
-  "version": "2.1.0",
-  "branch": "main",
+  "version": "2.1.1",
+  "branch": "2.1",
   "types": "./opensearch_dashboards.d.ts",
   "tsdocMetadata": "./build/tsdoc-metadata.json",
   "build": {