Revert "Updated multiple-choice interaction type to matching per group"

Reverting with Jono's approval

This reverts commit cece37d1619bf434c9cd6e45c784320a499a0ff4.
fix example based on normative spec language

choice, not multiple-choice is listed here:

https://github.com/adlnet/xAPI-Spec/blob/master/xAPI.md#interactionType