William Jamieson as new affiliated package editor

[Moritz Guenther]

Hi,

now that Pey Lian is part of the Coco, she decided to resign as
affiliated package editor to make some free time for her new role. We
asked the community for nominations for this role and are glad that
William Jamieson is willing to serve Astropy by curating the affiliated
package ecosystem.

Derek Homeier stays on for now as second affiliated package editor, so
the Coco nominates Derek and William to fill this role in the future:

https://github.com/astropy/astropy.github.com/pull/511

This PR will stay open for two weeks, so you can leave any comments
there or contact the Coco with further suggestions (Derek is on the
Coco, too, so we may look for a second person to replace Derek in the
future!).

Thanks to Pay Lian for her work in this role and thanks to William for
his willingness to take over!

Yours,

Moritz

(For the Astropy Coordination Committee)