I ended up reading the Webpack 1 documentation for several weeks after 2 came out. I'd see the warning, go "oh, I better not use Webpack 1 then", and continue reading its docs. Cue lots and lots of head scratching.
Webpack developers: if you're going to release a new set of documentation for 3, then please, please make this clear.
[0]: For example, https://webpack.github.io/docs/code-splitting.html. "webpack v1 is deprecated. We encourage all developers to upgrade to webpack 2." There's a link, sure, but I didn't follow it because I had no reason to think I wasn't already on the Webpack 2 docs page. grumble grumble