Fixed Backport section in developer guide (opensearch-project#1048)

Signed-off-by: Prabhat Sharma <[email protected]>
Co-authored-by: Prabhat Sharma <[email protected]>

DEVELOPER_GUIDE.md

@@ -77,6 +77,10 @@ In the base OpenSearch Dashboards directory, run
 
   - Runs the Cypress test runner
 
-### Backport
+### Backports
 
-- [Link to backport documentation](https://github.com/opensearch-project/opensearch-plugins/blob/main/BACKPORT.md)
+The Github workflow in [`backport.yml`](.github/workflows/backport.yml) creates backport PRs automatically when the
+original PR with an appropriate label `backport <backport-branch-name>` is merged to main with the backport workflow
+run successfully on the PR. For example, if a PR on main needs to be backported to `1.x` branch, add a label
+`backport 1.x` to the PR and make sure the backport workflow runs on the PR along with other checks. Once this PR is
+merged to main, the workflow will create a backport PR to the `1.x` branch.