Make list of people with write access public

[michielbdejong]

When requesting a review, you need to include at least 2 people with write access, and I couldn't find that information anywhere, would be good to make it transparent, especially if we soon want to vote about electing new people for spec editor roles.

[michielbdejong]

@Mitzi-Laszlo

[michielbdejong]

Just got a reply from Kjetil, it's the Solid team members, so the current list is: @kjetilk @RubenVerborgh @justinwb @Mitzi-Laszlo @timbl.

So each PR needs to be reviewed first by experts who can actually tell if the changes are correct or not, and then they also need to be approved with 2 out of 5 votes from that list.