[TASK] Document that UTF-8 is the only supported encoding.
[TASK] Document that UTF-8 is the only supported encoding.

Synchro/emogrifier,jjriv/emogrifier,OzzyCzech/emogrifier,iFixit/emogrifier,sanderkruger/emogrifier,Seldaek/emogrifier,MyIntervals/emogrifier,ernsto/emogrifier,ricardofiorani/emogrifier