(github) introduce pull request template (#81)

Co-authored-by: Kent C. Dodds <me+github@kentcdodds.com>

Author: imcodingideas

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,15 @@
+<!-- Summary: Put your summary here -->
+
+## Test Plan
+
+<!-- What steps need to be taken to verify this works as expected? -->
+
+## Checklist
+
+- [ ] Tests updated
+- [ ] Docs updated
+
+## Screenshots
+
+<!-- If what you're changing is within the app, please show before/after.
+You can provide a video as well if that makes more sense -->