Add Markdown formatting at end of ODK seed command

It would make it much easier to get up and running with ODK if the Markdown that it produced were nicely formatted.

- [ ] Add `npx --yes prettier --check --prose-wrap always --write '**/*.md'` to seed workflow
- [ ] Add proper code highlighting wherever possible
- [ ] Add the option to include a markdown linting GHA test

Start at the ODK seed workflow and inspect the Markdown files it produces. Run the listed Prettier command to establish the current formatting, then check how code blocks are represented and how GitHub Actions tests are configured. Done means the seed output is formatted, code highlighting is added where possible, and a Markdown linting workflow option is included.

Written by the indexing model from the issue text.