new: Write a Get Involved/Request New Features doc

[joelhans]

https://athensresearch.gitbook.io/handbook/community/get-involved/learning-at-athens-academy-education/request-new-features

https://github.com/athensresearch/handbook/blob/main/community/get-involved/learning-at-athens-academy-education/request-new-features.md

[joelhans]

Do we have a resource that gives guidelines on what makes a good or helpful feature request?

From here: https://github.com/athensresearch/athens/discussions/826#discussioncomment-778473

This document should definitely detail what makes a good feature request.