docs: add badges to README

Added badges for npm version and CI status.

Author: simonsmith

README.md

@@ -2,6 +2,9 @@
 
 Stylelint plugin that validates CSS custom properties in CSS modules to ensure they follow a component-based naming convention.
 
+![npm version](https://img.shields.io/npm/v/@simonsmith/stylelint-component-custom-property)
+![CI](https://github.com/simonsmith/stylelint-component-custom-property/actions/workflows/ci.yml/badge.svg)
+
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