Add pull request template (#2463)

Encourages students to provide their name, the list of user stories they implemented and prompts them to write a good README.

.github/pull_request_template.md

@@ -0,0 +1,24 @@
+# Your name
+
+Please write your full name here to make it easier to find your pull request.
+
+# User stories 
+
+Please list which user stories you've implemented (delete the ones that don't apply).
+
+- [ ] User story 1: "I want to instruct a plane to land at an airport"
+- [ ] User story 2: "I want to instruct a plane to take off from an airport and confirm that it is no longer in the airport"
+- [ ] User story 3: "I want to prevent landing when the airport is full"
+- [ ] User story 4: "I would like a default airport capacity that can be overridden as appropriate"
+- [ ] User story 5: "I want to prevent takeoff when weather is stormy"
+- [ ] User story 6: "I want to prevent landing when weather is stormy"
+
+# README checklist
+
+Does your README contains instructions for
+
+- [ ] how to install,
+- [ ] how to run,
+- [ ] and how to test your code?
+
+[Here is a pill](https://github.com/makersacademy/course/blob/main/pills/readmes.md) that can help you write a great README!