4.0 release

Hi, Browserslist users. As I promised every API changes will be discussed with the community and voted.

I am planning to release 4.0 with these changes:

1. Allow selecting Node.js versions with node 10, node 9.5, node 9.5.1 or maintained node versions queries. Browserslist result now could contain node x.x.x values. Be sure that your tool will not fall on this values.
2. If caniuse-lite npm package was not updated for more than 6 months, Browserslist will warn the user about it and suggest to update it. I think using latest Can I Use data is very important or all queries like last 2 versions will lose sense and will be unpredictable for new developers.

Approved (every tool has 1 vote, Autoprefixer and eslint-plugin-compat have same vote). To accept changes we need more than 50%.

• Autoprefixer @ai
• babel-preset-env @yavorsky @hzoo
• postcss-preset-env @jonathantneal
• postcss-normalize @jonathantneal
• eslint-plugin-compat @amilajack
• stylelint-no-unsupported-browser-features @ismay
• browserslist-ga @dmfrancisco
• browserslist-useragent @pastelsky
• cssnano @evilebottnawi

[ai]

Released https://github.com/browserslist/browserslist/commit/2a66017404213d054c39bfdf75e8d34ebe278cac

[ai]

@jonathantneal great suggestions. Could you send PR (my secret plan to increase contributors stats for this repo 😄)

(This diff was for everyone to show the code changes, I fixed docs after a comment 😄. And it was my mistake, it is good idea to review my English in docs)