Adding documentation for backport (#159)

Signed-off-by: Vacha Shah <vachshah@amazon.com>
(cherry picked from commit 262f05a)

MAINTAINERS.md

@@ -5,6 +5,7 @@
   - [Prioritize Security](#prioritize-security)
   - [Review Pull Requests](#review-pull-requests)
   - [Triage Open Issues](#triage-open-issues)
+  - [Backports](#backports)
   - [Be Responsive](#be-responsive)
   - [Maintain Overall Health of the Repo](#maintain-overall-health-of-the-repo)
   - [Use Semver](#use-semver)
@@ -50,6 +51,10 @@ All repositories in this organization have a standard set of labels, including `
 
 Use labels to target an issue or a PR for a given release, add `help wanted` to good issues for new community members, and `blocker` for issues that scare you or need immediate attention. Request for more information from a submitter if an issue is not clear. Create new labels as needed by the project.
 
+### Backports
+
+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. To backport a PR to `1.x`, add a label `backport 1.x` to the PR, once this PR is merged to main, the workflow will create a backport PR to the `1.x` branch.
+
 ### Be Responsive
 
 Respond to enhancement requests, and forum posts. Allocate time to reviewing and commenting on issues and conversations as they come in.