Greeting bot

During ZuriHac I discussed with Teo and some GHC steering committee members that it might be helpful to add an automated response to every proposal that points the proposer to the next step in the process (submitting their proposal).

I've created a rough draft of such a "workflow" in my fork:

https://github.com/noughtmare/core-libraries-committee/blob/main/.github/workflows/greeting.yml

You can see the result in this test issue:

https://github.com/noughtmare/core-libraries-committee/issues/3

The text is still rough, so please suggest improvements!

Start with .github/workflows/greeting.yml in the linked fork and compare it with the result shown in test issue #3. Review the proposal text and discussion for improvements to the automated response; done means the workflow gives proposers a clear next step with polished wording.

Written by the indexing model from the issue text.