Update documentation for Boot

Recently luminus gained support for creating a project built with boot. Right now, understandably, the luminus website only has documentation for lein projects. It would be great to document how to use boot with luminus as well.

What would be the best way to go about this?

We could simply have both in one page, but for pages like the ClojureScript documentation, this takes up a lot of space, since we need to specify the boot tasks required and the commands to run them (including adding an app.cljs.edn file). There aren't too many pages like this, so it may be worth just giving people a bit more to read through.

Alternatively, we could consider adding javascript or clojurescript to the project and allowing users to set whether or not they use boot or lein, and then displaying only the documentation for that version. This is a bit more complicated, and thus more likely to break, but cleaner to the end user if doesn't break.

Start by reading the existing ClojureScript documentation and the linked luminus-template pull request. Compare the current Leiningen instructions with the Boot tasks and app.cljs.edn setup mentioned in the issue, then decide whether to combine or separate the guidance. Done means Boot users can follow the relevant documentation pages successfully.