Amend ReadMe to reflect 2.x builds (#118)

Signed-off-by: Sarthak Aggarwal <sarthagg@amazon.com>

Author: sarthakaggarwal97

README.md

@@ -1,5 +1,5 @@
-[![Backward Compatibility Checks](https://github.com/opensearch-project/custom-codecs/actions/workflows/ci.yml/badge.svg?branch=main)](https://github.com/opensearch-project/custom-codecs/actions/workflows/ci.yml)
-[![Publish snapshots to maven](https://github.com/opensearch-project/custom-codecs/actions/workflows/publish-maven-snapshots.yml/badge.svg?branch=main)](https://github.com/opensearch-project/custom-codecs/actions/workflows/publish-maven-snapshots.yml)
+[![Backward Compatibility Checks](https://github.com/opensearch-project/custom-codecs/actions/workflows/ci.yml/badge.svg?branch=2.x)](https://github.com/opensearch-project/custom-codecs/actions/workflows/ci.yml)
+[![Publish snapshots to maven](https://github.com/opensearch-project/custom-codecs/actions/workflows/publish-maven-snapshots.yml/badge.svg?branch=2.x)](https://github.com/opensearch-project/custom-codecs/actions/workflows/publish-maven-snapshots.yml)
 
 # Custom Codecs
 Custom Codecs plugin makes it possible for users to provide custom Lucene codecs for loading through Apache Lucene's `NamedSPILoader`.