Add in PR Template

[CesiumBen]

Summary

This PR adds in a PR template for making PR's for each tutorial. While setup is unorthodox and we wouldn't center PR's around each tutorial, typically they would.

Author checklist

• Tutorial for N/A (Documentation)
• Has the new tutorial been integrated into the main level? N/A
• Have you done a full self-review of the code? N/A
• Have you tagged a primary reviewer? N/A
• Are there any remaining tasks to do or blocking questions to answer before we can merge this? No

Testing plan

Review documentation

Reminders for reviewers

Thank you for taking the time to review this PR. By approving a PR you are taking as much responsibility for these changes as the author. Please keep these points in mind throughout the review process:

• Review and run all parts of the test plan on this branch and verify it matches expectations.
• Review the code and make sure you do not have any remaining questions or concerns. You should understand why this code change fixes the issue and agree that it's the best approach to doing so.
• Review the automated tests and make sure there are no missing tests or edge cases.
• When you feel this is ready bump it to a second reviewer or merge.

[xuelongmu]

Thanks @CesiumBen! This looks good.