Update explainers to reflect latest discussions

[addyosmani]

Trying to summarize a few discussions before filing PRs:

1. We are now going to use the importance attribute instead of group. Related to Converge to a single group attribute, with values indicating before and after #6
2. We will use the following importance buckets: critical, high, medium, low, unimportant Group names bikeshed #7
3. We do want a JS equivalent for what we're doing here, but have not concretely explored this yet. Support SW install usage case via new property on Request interface #11 touches on this. We can say "There is a desire to explore priority hints importance in terms of fetch.". Perhaps we should just reference that issue or another to encourage continuing that discussion.
4. V0 will not explore a resource throttling algorithm, which came up in Questions following initial implementation #10. Does that sound reasonable? We've had some input on this topic but unsure if enough to make a call here.

[yoavweiss]

Thanks for summarizing the different discussions! This all makes sense to me.
Regarding 4), UAs could apply throttling on low priority third parties in H2 regardless of explicit hints. It's also something we can explore using SW.

[addyosmani]

Thanks for summarizing the different discussions!

Cheers!

4), UAs could apply throttling on low priority third parties in H2 regardless of explicit hints. It's also something we can explore using SW.

This is a useful reminder and something good to be aware of.