Added pull request template (#6)

Author: francescalb

.github/pull_request_template.md

@@ -0,0 +1,19 @@
+# Description:
+<!-- Summary of change, including the issue(s) to be addressed. -->
+
+## Type of change:
+<!-- Put an `x` in the box that applies. -->
+- [ ] Bug fix.
+- [ ] New feature.
+- [ ] Documentation update.
+
+## Checklist for the reviewer:
+<!-- Put an `x` in the boxes that apply. These can be filled by reviewer after the PR is created. -->
+
+This checklist can be used as a help for the reviewer.
+
+- [ ] Is the change limited to one issue?
+- [ ] Does this PR close the issue?
+- [ ] Is the code easy to read and understand?
+- [ ] Do all new feature have an accompanying new test?
+- [ ] Has the documentation been updated as necessary?