Pull Request notification emails now being sent to commits lists


I’ve turned on our PR emailer, so it’s now sending pull request notifications to the commits lists. The script we use to format and send the emails is https://github.com/llvm/llvm-admin/blob/main/AWS/Lambda/PREmailer/pr_emailer.py. If you have suggestions for improvements to the email formats or you notice any issues with the emails, you can create a pull request or file a bug.