Re-think Contributors table

Opening this issue to discuss if you would like to open the door to redesign the approach on how many contributors are shown in the table and what criterias to follow to do so.

The origin of the discussion is this one:

> And even better: I think we should keep track of how often a contributor was thank for each contribution, even if we don't expose it. For larger projects, it makes sense to shorten the contributors table eventually, and we could make it based on the time of the last contribution by a user.

_Originally posted by @gr2m in https://github.com/all-contributors/app/issues/358#issuecomment-848304512_