Add comment cc-ing teams/devs in issues

[phillipj]

It seems the auto labelling of node PRs has settled and working pretty good atm, are we ready to start cc-ing the sub-system maintainers?

Refs nodejs/node#6694

/cc @Fishrock123

[phillipj]

Who to cc for reference: https://github.com/nodejs/node/blob/master/doc/onboarding-extras.md

[Trott]

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