doc: add pull request template

Signed-off-by: Jan Larwig <jan@larwig.com>

Author: tuunit

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,15 @@
+<!--- Provide a general summary of your changes in the Title above -->
+## Description
+
+<!--- Describe your changes in detail -->
+
+## Checklist:
+
+<!--- Go over all the following points, and put an `x` in all the boxes that apply. -->
+<!--- If you're unsure about any of these, don't hesitate to ask. We're here to help! -->
+
+- [ ] I have bumped the version in the Chart.yaml according to [Semantic Versioning](https://semver.org).
+- [ ] I have updated the documentation/CHANGELOG at the bottom of the Chart.yaml
+- [ ] I have [signed off](https://github.com/apps/dco) all my commits.
+- [ ] (Optional) I have updated the Chart.lock for dependency updates
+- [ ] (Optional) I have implemented helm tests for new feature flags