feat(README): add npm version and downloads badges

This commit adds two badges to the README file: one for the npm
version and one for the npm downloads. These badges provide quick
access to the package's npm page and indicate its popularity.

Author: ryoppippi

README.md

@@ -1,5 +1,8 @@
 # svelte-preprocess-css-modules
 
+[![npm version](https://img.shields.io/npm/v/svelte-preprocess-css-modules?color=yellow)](https://npmjs.com/package/svelte-preprocess-css-modules)
+[![npm downloads](https://img.shields.io/npm/dm/svelte-preprocess-css-modules?color=yellow)](https://npmjs.com/package/svelte-preprocess-css-modules)
+
 Successor of [svelte-preprocess-cssmodules](https://github.com/micantoine/svelte-preprocess-cssmodules)
 
 ## Installation