Hi! I'd like to offer my help for adding instructions to scala-js.org on how to debug Scala.js code in the browser using source maps. I've seen there are [plans](https://www.scala-js.org/doc/planning.html) to add that kind of documentation but so far I've found nothing related on the website. I'd be happy to collect expertise, caveats, and SBT configs, write that up in a step-by-step guide and create a pull request. Regarding IDEs, I'd suggest, we include instructions for debugging in IntelliJ and Chrome DevTools.