About page for 3.6.

 * Colorful New Theme
 * Write with Confidence
 * Support for Audio and Video
 * Under the Hood

Screenshots to come. Under the Hood to be finalized and thus not yet offered for translation.

props aaroncampbell, coffee2code, duck_, lessbloat, markjaquith, nacin, samuelsidler, siobhan.
see #24832.



git-svn-id: http://core.svn.wordpress.org/trunk@24802 1a063a9b-81f0-0310-95a4-ce76da25c4cd