Adds PR template (#196)

.github/pull_request_template.md

@@ -0,0 +1,38 @@
+# I have made things!
+
+<!--
+Hi, thanks for submitting a Pull Request. We appreciate it.
+
+Please, fill in all the required information
+to make our review and merging processes easier.
+
+Cheers!
+-->
+
+## Checklist
+
+<!-- Please check everything that applies: -->
+
+- [ ] I have double checked that there are no unrelated changes in this pull request (old patches, accidental config files, etc)
+- [ ] I have created at least one test case for the changes I have made
+- [ ] I have updated the documentation for the changes I have made
+- [ ] I have added my changes to the `CHANGELOG.md`
+
+## Related issues
+
+<!--
+Mark what issues this Pull Request closes or references.
+
+Format is:
+- Closes #issue-number
+- Refs #issue-number
+
+Example. Refs #0
+Documentation: https://blog.github.com/2013-05-14-closing-issues-via-pull-requests/
+-->
+
+<!--
+If you have any feedback, just write it here.
+
+It can be whatever you want!
+-->