Improve requirements for full member vs provisional member

The membership count should also be separated as it's a different topic.

Thinking on it more there's a bigger problem in that provisional membership isn't clearly defined.

Per discussion with Larowlan, moving this to the Governance issue queue.

Larowlan's feedback was that the charter document is supposed to be vague and not get into specifics too much. However, the paragraph noted above still needs clarification as it's still vague and combines too many topics in one paragraph.

@DamienMcKenna, can you provide an MR or the changes you would like to have made?