Minor fix on doc theme version 1.3.7.7

Hi.
At doc theme, file 404.php is a typo on line 13
<p><?php _e('If you're lazy, or don't feel social, you could', 'doc'); ?>:</p>
single quotes into _e('.
Replaced the line with
<p><?php _e("If you're lazy, or don't feel social, you could", "doc"); ?>:</p>

Cheers Lena