Proposal: create an account for a GitHub bot.

[bjohansebas]

Having an account for a bot could be a good idea; it would automate many tasks and prevent errors like expressjs/expressjs.com#1553, or help keep the .github repositories synchronized. Perhaps this account could handle releases when that can be automated, or add the labels that are being attempted to be added in #300 and expressjs/expressjs.com#1642.

The account would only have triage permissions in the three organizations.