#33 Add example to Slack modal for new puzzle

[FionaDL]

This addresses the issue with inconsistency in adding puzzles. We have taken the template that @etagwerker creates and are showing it in the Slack modal for easy reference for people who are adding puzzles. We did try first to read the template and use that, but it was having timeout errors and taking longer then necessary (a few seconds).

QA:
You will need to QA this locally by:

• Running ngrok
• Changing the /ror-puzzle command url in the Slack application to coordinate with your ngrok
• Check the modal to see that the examples mentioned and show how to create puzzles with code snippets

[etagwerker]

Looks good, thanks! 👍🏻