Closes #24006, addresses #23991 (closed).
This PR aims to make it more explicit what needs to be included for Bootstrap's CSS and JS to work. I've added new subheadings, updated some body copy, and added a <details> block to list out all our JS components for those who are curious. I thought about always showing it, but that kinda defeats the purpose of a quick start guide I think.
/cc @bkdotcom