Update contributing to spotlight documentation

[corylown]

Description

This adds some details about becoming a contributor or committer to Spotlight, borrowing and adapting language from the Blacklight documentation: https://github.com/projectblacklight/blacklight?tab=contributing-ov-file#becoming-a-committer

[ebtoner]

@corylown - Maybe this is something that we can discuss at the next Spotlight community meeting?

[caaster]

@ebtoner Can you say more here by chance about the discussion you wish to have -- and any concerns? Our agenda is pretty full for our community meeting on 3/26, but we're happy to make space for this if we can have a brief, well-defined and facilitated discussion.

[ebtoner]

This change has implications for community participation, so it makes sense to me that it would be discussed by the community first.

One area that might need a bit more clarification is the invitation to become a committer. Who makes that decision? Do you automatically become a committer by participating in a community sprint?

Perhaps @JesiBuell79 can weigh in here. We were just discussing this in the Sustainability Working Group meeting, so perhaps it can be included in her agenda item.

[caaster]

@ebtoner Thank you for raising the importance of this issue. This topic is now on the agenda for our 3/26 community meeting, and Jesi will facilitate it.