Merge pull request #555 from pixiv/naporitan/storybook-foundation-docs

chore(foundation): migrate docs

packages/foundation/src/README.mdx

@@ -0,0 +1,37 @@
+import { Meta } from '@storybook/addon-docs'
+
+<Meta title="foundation/README" />
+
+# @charcoal-ui/foundation クイックスタート
+
+[![npmバッジ](https://img.shields.io/npm/v/@charcoal-ui/foundation?label=%40charcoal-ui%2Ffoundation&style=flat-square&logo=npm)](https://www.npmjs.com/package/@charcoal-ui/foundation)
+
+## インストール
+
+### npm
+
+```bash
+npm install @charcoal-ui/foundation
+```
+
+### yarn
+
+```bash
+yarn add @charcoal-ui/foundation
+```
+
+### pnpm
+
+```bash
+pnpm add @charcoal-ui/foundation
+```
+
+### bun
+
+```bash
+bun add @charcoal-ui/foundation
+```
+
+## 概要
+
+`@charcoal-ui` で利用されるプリミティブな型定義や値を提供します。