chore: update PR template to suggest cherry-pick releases (argoproj#1…

…6560)

Signed-off-by: Jesse Suen <[email protected]>

.github/pull_request_template.md

@@ -13,11 +13,12 @@ Checklist:
 * [ ] I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
 * [ ] Does this PR require documentation updates?
 * [ ] I've updated documentation as required by this PR.
-* [ ] Optional. My organization is added to USERS.md.
 * [ ] I have signed off all my commits as required by [DCO](https://github.com/argoproj/argoproj/blob/master/community/CONTRIBUTING.md#legal)
 * [ ] I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
 * [ ] My build is green ([troubleshooting builds](https://argo-cd.readthedocs.io/en/latest/developer-guide/ci/)).
 * [ ] My new feature complies with the [feature status](https://github.com/argoproj/argoproj/blob/master/community/feature-status.md) guidelines.
 * [ ] I have added a brief description of why this PR is necessary and/or what this PR solves.
+* [ ] Optional. My organization is added to USERS.md.
+* [ ] Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).
 
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