kafka/PULL_REQUEST_TEMPLATE.md

*More detailed description of your change,
if necessary. The PR title and PR message become
the squashed commit message, so use a separate
comment to ping reviewers.*

*Summary of testing strategy (including rationale)
for the feature or bug fix. Unit and/or integration
tests are expected for any behaviour change and
system tests should be considered for larger changes.*

### Committer Checklist (excluded from commit message)
- [ ] Verify design and implementation 
- [ ] Verify test coverage and CI build status
- [ ] Verify documentation (including upgrade notes)