Pause Ruben Verborgh's involvement as an Editor

[RubenVerborgh]

I'd like to pause my involvement as an Editor.
I feel lucky to have worked on the specs with a great team, and the groundwork is there now.
0.9 was a great milestone for us all.

Lately, I've noticed that my text contributions have become less due to other Solid commitments, so I feel it would no longer be fair to be listed next to people who are writing significantly more text than I am.

You can still count on my availability for reviewing texts etc., and perhaps I will apply again in the future if my work brings me back to specification texts. In any case, my involvement with Solid will remain at least 100% 😎

[csarven]

Only want to comment on a technicality (and it can be followed up in a separate PR for #287 ): It's be great to include a column along the lines of an "active period" to be transparent as well as to ensure that contributors are credited (as opposed to just disappearing or being lost in the commit logs).