Add PR template (#88)

* Add PR template file

* Add content to PR template

.github/pull_request_template.md

@@ -0,0 +1,21 @@
+**Related to:** <!-- Add links to related issues etc. here -->
+
+## Description
+
+<!-- Briefly describe what this PR does. Use dot points or a check list if needed -->
+
+## Checklist
+
+**Before review**
+
+- [ ] Update and regenerate man pages
+- [ ] Add/update tests
+- [ ] Add/update examples in vignettes
+- [ ] Pass CI checks
+
+**Before merge**
+
+- [ ] Update architecture vignette
+- [ ] Update development vignette
+- [ ] Update features in `README`
+- [ ] Update `CHANGELOG`