Update README

Author: adamwathan

README.md

@@ -97,5 +97,4 @@ There are a few items on our todo list still though that we are still implementi
 
 - The `prefix`, `important`, and `separator` options are not supported yet.
 - Advanced PurgeCSS options like `safelist` aren't supported yet since we aren't actually using PurgeCSS. We'll add a way to safelist classes for sure though.
-- Third party plugins that add variants using the `modifySelectors` API aren't supported yet. Plugins that add variants without that API do work though.
 - You can only `@apply` classes that are part of core, generated by plugins, or defined within a `@layer` rule. You can't `@apply` arbitrary CSS classes that aren't defined within a `@layer` rule.