Document all feature names and warn on unrecognized features

[ghost]

Hey there, just wasted a good chunk of the day trying to debug why custom media queries weren't being transpiled. It turns out I was trying to use the feature custom-media in my config, when in fact the feature is named custom-media-queries.

That might sound like a foolish mistake... except the name of the feature is simply not documented anywhere that I can tell:

• It's not in README.md or any other documentation in the repo

• If I check https://preset-env.cssdb.org/features#custom-media-queries, I can see that the feature exists, but not how to activate it:

  

  (If I hit the "plugin" link above, the plugin that preset-env wraps is in fact named "postcss-custom-media" -- not "postcss-custom-media-queries"! -- misleading me further.)

postcss-preset-env also happily accepts non-existent feature names in its config without raising a warning, which exacerbates the issue. If it had refused to run or raised a warning when I tried to activate the nonexistent custom-media feature, that would've at least saved me some debugging time!

[skrhlm]

Thank you so much for creating this issue. This saved my day.

I was going crazy over why custom media queries was being skipped. This helped me figure out that it actually ( seems very clear now in retrospect ) does not polyfill them since it's only in stage 1 and the default for postcss-preset-env is {stage: 2}.

[Antonio-Laguna]

This repository is getting archived. If this issue keeps happening please re-open on @csstools/postcss-plugins and we'll do our best to fix it!