Add some tutorials for JS development

[f-f]

The docs used to contain some tutorials for getting a small JavaScript project up and running with various bundlers and setups.

Over time that section grew to take a considerable chunk of the docs, and it was unwieldy to maintain, so it was dropped during the rewrite of the docs.

I am not sure at all if we should include such extensive documentation for how to bootstrap a project, as it feels like it would be more suited for inclusion in the cookbook and we could just redirect there? (cc @JordanMartinez)

[JordanMartinez]

That might be a good idea. At the very least, the new spago is the kind of tool I wanted for the cookbook, as each recipe is technically its own package.

[flip111]

It would also be good if it were easy to switch to a production build. Sure there is bundle but the output file still has to be wired up. Also production builds can require different backends like recommended here https://github.com/aristanetworks/purescript-backend-optimizer Not sure how this scenario can be implemented in the new spago

[fsoikin]

That documentation seems indeed super extensive to me. For example, if you're starting a whole new project, why would you use non-latest version of PureScript? And the different bundlers with so much configuration. For a basic "get up and running" setup, it seems to me, just spago init is enough. And even if you wanted to make a web app, - for example, our Elmish getting started guide fits on one screen.