Add me as an editor of CSSOM as resolved in the Berlin F2F.

See https://logs.csswg.org/irc.w3.org/css/2018-04-11/#e999920

Author: emilio

cssom-1/Overview.bs

@@ -12,6 +12,7 @@ Work Status: Exploring
 Shortname: cssom
 Level: 1
 Editor: Daniel Glazman, Disruptive Innovations http://disruptive-innovations.com/, daniel.glazman@disruptive-innovations.com, w3cid 13329
+Editor: Emilio Cobos Álvarez 106537, Mozilla, emilio@mozilla.com
 Former Editor: Simon Pieters, Opera Software AS http://www.opera.com, simonp@opera.com
 Former Editor: Glenn Adams, Cox Communications, Inc. http://www.cox.com, glenn.adams@cos.com, http://www.w3.org/wiki/User:Gadams
 Former Editor: Anne van Kesteren, Opera Software ASA http://www.opera.com, annevk@annevk.nl, https://annevankesteren.nl/