Added docker-compose.yml for using Opensearch backend

[williamtrelawny]

Even though we've released Data Node, using Opensearch as an indexing backend is still supported, so still deserves to have a deployment configuration reference

Notes for Reviewers

• [x] The commit history must be preserved - please use the rebase-merge or standard merge option instead of squash-merge
• [x] Sync up with the author before merging