[MSE] Stepping down as MSE editor

Hi,

I wanted to let people know that I'd like to step down from being the MSE
editor. I left the Chrome team ~5 months ago and I had hoped that I would
be able to keep up with my MSE spec editing duties. As time has gone on
though I have found that it has been increasingly difficult for me to find
time to focus on MSE. My current responsibilities at Google don't involve
the web platform at all so context-switches to MSE work are particularly
difficult. Since I cannot provide the attention to this work that I have in
the past, I think it is best for me to step down and let someone else take
over.

In order to facilitate the transition to a new editor, I'd be happy to
answer any questions he/she may have and walk them through the docs and the
process I've followed over the years.

Finally, I'd like to thank everyone who has participated in the MSE spec
process. We have come a long way together since I proposed it to WebKit
~3.5 years ago and Mark, Adrian, and I proposed it to the W3C ~3 years ago.
I have appreciated your guidance, support and patience.

Aaron