Added issue and pull request templates (#355)

.github/pull_request_template.md

@@ -0,0 +1,18 @@
+## Problem Statement
+
+What is the problem you're trying to solve?
+
+## Related Issue
+
+Fixes #...
+
+## Proposed Changes
+
+How do you like to solve the issue and why?
+
+## Checklist
+
+- [ ] Commits are signed with `git commit --signoff`
+- [ ] Changes have reasonable test coverage
+- [ ] Tests pass with `make test`
+- [ ] Helm docs are up-to-date with `make helm-docs`