Clarify live coding vs. live demonstration

### How could the content be improved?

Per #1558 there has been considerable discussion about the merits of referring to Carpentries-style teaching as "live coding" (current practice) vs. "live demos". Live coding is consistent with published literature (mainly in computer science and engineering education) and is how we've done it. Live demos/demonstrations is technically more inclusive of Carpentries workshops that do not focus on coding (spreadsheets, OpenRefine, etc.). The PR is being closed because of the length of time it's existed without resolution, but the question is worth revisiting at a later time.

### Which part of the content does your suggestion apply to?

episodes/17-live.md

Start by reading episodes/17-live.md and the discussion referenced in #1558 to understand the competing terms and their teaching-context implications. The work is done when the terminology decision is resolved and the relevant content is updated consistently.

Written by the indexing model from the issue text.