pr: Create pull_request_template.md (#27)

Add a pull request template for better PR submissions.

.github/pull_request_template.md

@@ -0,0 +1,28 @@
+## Description
+
+Describe the changes made in this PR.
+
+---
+
+## Testing
+
+- [ ] Code has been tested
+- [ ] Existing tests pass
+
+Notes:
+<!-- Add anything relevant about testing -->
+
+---
+
+## Documentation
+
+- [ ] Documentation updated if needed
+
+Notes:
+<!-- Add anything relevant about documentation -->
+
+---
+
+## Additional Notes
+
+<!-- Anything reviewers should know -->