Consolidate dev mode documentation #423
Description
Throughout the docs there are many references to dev mode, some of them describe the legacy dev mode that does not work in any actual browsers.
You will spend most of your development time running your application in development mode, which means that you are interacting with your GWT application without it having been translated into JavaScript.
-- https://www.gwtproject.org/doc/latest/DevGuideCompilingAndDebugging.html
All information about the defunct dev mode should be removed from the docs (or if deemed necessary, move it to some "history" section) to reduce confusion for users.