Remove old plugin

Author: ai

README.md

@@ -476,12 +476,9 @@ module.exports = {
 
 ### VS Code
 
-* [`csstools.postcss`] adds support for PostCSS, `postcss-preset-env`
-  and CSS Modules.
-* [`mhmadhamster.postcss-language`] is a more modern alternative.
+* [`mhmadhamster.postcss-language`] adds PostCSS and SugarSS support.
 
 [`mhmadhamster.postcss-language`]: https://marketplace.visualstudio.com/items?itemName=mhmadhamster.postcss-language
-[`csstools.postcss`]: https://marketplace.visualstudio.com/items?itemName=csstools.postcss
 
 
 ### Atom