Add postcssplugin keyword
Add postcssplugin keyword

alanev/postcss-filter,cardinalcss/cardinalcss-module-generator,wilsson/postcss-url-versioner,postcss/postcss-plugin-boilerplate,wilsson/postcss-url-versioner,DavidWells/postcss-plugin-boilerplate,manmohan-bisht/my-postcss,dichuvichkin/postcss-eol,hallvors/postcss-flexboxfixer,thomassittig/postcss-split-up-by-rules,ryanbahniuk/postcss-rails-asset-urls,tommillard/postcss-hsb-adjust