PostCSS website #391

Let’s collect ideas about future PostCSS website.

1. Plugins list (even with search like in gulp) is a lame way. We need some wizard (of course list will exists too):
   1. You select basement: preprocessors or/and CSS4.
   2. You select architecture: BEM, CSS Modules, etc.
   3. You select a builder: Gulp, webpack, grunt, etc.
   4. Pick some extra sugar.
   5. We will get you a exactly code to copy-paste to your build process. For example, only gulp-cssnext with some sugar plugin additions if you select CSS4, BEM, Gulp and not so many additions.
2. AST explorer for plugin developer. You put a CSS and get PostCSS AST with references.
3. Migration guide
4. Docs with good formation.
5. Playground based on postcss-use.