fix(control-props): typo (#129)

exercises/08.control-props/01.problem/toggle.tsx

@@ -24,7 +24,7 @@ export function toggleReducer(state: ToggleState, action: ToggleAction) {
 }
 
 export function useToggle({
- // 🐨 add a the `on` and `onChange` options here.
+ // 🐨 add the `on` and `onChange` options here.
  // 💰 you can alias it to `controlledOn` as we do in the Toggle component
  // below to avoid "variable shadowing."
  initialOn = false,