Add item regarding updating the group label

I noticed that the ~"group::ecosystem" label description still referred to the Enablement stage, so I changed it to Create.

I assumed there's some point in the process for moving stages where a checkpoint could be added, then I found #432 (closed), and so it seemed this template is as good a place as any to add a checklist item.

It could even be automated instead? If all the group labels follow the same template (or were updated to) the an update could be applied as part of a one-off policy?

WDYT @gl-quality/eng-prod?