Update authors list

[peterthomassen]

I feel that the authors' list should roughly reflect contributions to the text. One way is measuring lines per author:

$ git blame -w -M -C -C --line-porcelain draft-ietf-dnsop-dns-catalog-zones.md | grep -I '^author ' | sort -f | uniq -ic | sort -nr
    586 author Willem Toorop
     50 author Peter Thomassen
     29 author Peter van Dijk
     25 author Mukund Sivaraman
     20 author Libor Peltan
      2 author Ray Bellis

[wtoorop]

Resolverd in @5b32910