Refine eligibility criteria for roles

[camerons]

Comment from roles.md review:

*   Submit pull requests which have been accepted and merged by other committers. Typically one large, three medium, or five small pull requests over three months.

@Loquacity
Do we need to define what large, medium, and small PRs are? I guess small is typos, and large is structural changes, but not sure what medium might be.

@jaredmorgs
Definitely something to capture as part of iteration 2 (or even I3) of this document.

@mgan59
Also, track people's contributions from the discussion side -- opening/commenting on Issues and on PRs. As not every contributor is going to be able to open a PR. This means we aren't inclusive of less-experience individuals looking to become members.... Not sure if this means we change this from Committers to Contributors...

[camerons]

• Help with whatever unglamorous work that is required to keep the project moving forward.
  @Loquacity
  Personally, I like the term "plumbing" to describe this kind of work. I'm not sure any of what we do is particularly glamorous ;)

@mgan59
Fine with this being here for now, but feel like we should have a larger Core Values statement documented which would be inclusive of this idea. And those that don't embody those values probably shouldn't be members of the PSC.

[camerons]

Consider this comment:

Expectations of treasurers:

• Notify the PSC of Open Collective funding requests by raising a motion.
• AFTER receiving approval from the PSC, approve funding requests.
  @Loquacity
  Responsible financial management?

@jaredmorgs
Put that in as an alpha cut, then plan to refine the sentence/guidance in Alpha 0.1 or 0.2?