fix typos in initial code walk-through;
fix typos in initial code walk-through;

daiyi/re-frame,martinklepsch/re-frame,richardharrington/re-frame,daiyi/re-frame,richardharrington/re-frame,chpill/re-frankenstein,chpill/re-frankenstein,Day8/re-frame,Day8/re-frame,martinklepsch/re-frame,daiyi/re-frame,Day8/re-frame,martinklepsch/re-frame,richardharrington/re-frame,chpill/re-frankenstein