"elm reactor" instructions unclear

[CaptainZippy]

This issue is about the beginner experience.

In https://guide.elm-lang.org/install/elm.html one sees topics such as "elm reactor" and "elm make". If one runs "elm make" then "elm reactor", it is natural to open the index.html. This appears to work, but of course reload etc doesn't work. We need to navigate to src and open Main.elm for the nice stuff to work.

It would be nice to make this clear in the docs (BTW I couldn't find the source to those docs in github?)