Introduce web group issue triages

Created by: felixfbecker

We did these multiple times a while ago but haven't done one in a while. As we define our own goals for the team, long-term and for each iteration, I think it's even more important than before we all have a shared awareness of our issue backlog (which includes everything from bugs, feature requests, debt, perf problems and tooling problems) so we can make informed decisions on what goals to set and what to work on. I am therefor proposing we make this part of our process, through a PR to the handbook 🙂

Especially interested to hear from @marekweb and @twop if this would be helpful!