[CGCharter] Task Forces: define terms used in paragraph (convener, champion)

[trwnh]

The convener of a task force does NOT need to be the "champion" of a work item being coordinated in it, NOR do they need to be a Committer.

I imagine that "champion" is a reference to the staging process, but I'm not entirely sure I fully understand what "convener" means here. What does it mean to "convene" a task force, as opposed to:

• "schedule their own topic calls"
• "tag niche email threads"
• be "spun up" or "spun down"