Thus, we remove the -y/--yes options, which were kind of unintuitive,
and we add instead `-i/--interactive`. The quickstart commands remain
interactive by default, but can be silenced with `-I/--non-interactive`.
- More concise table of contents
- New intro
- Simpler make commands
- Fix a couple typos here and there
- Get rid of the default github issue template, and start using the
template created online.
