chore: add example for tree-shaking

examples/tree-shaking-create-react-app/package.json

@@ -0,0 +1,37 @@
+{
+  "name": "custom-styles",
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "scripts": {
+    "dev": "react-app-rewired start",
+    "build": "react-app-rewired build",
+    "analyze": "source-map-explorer 'build/static/js/*.js'"
+  },
+  "dependencies": {
+    "@zeit-ui/react": "^1.5.0-rc.0",
+    "react": "^16.13.1",
+    "react-dom": "^16.13.1"
+  },
+  "devDependencies": {
+    "@types/react": "^16.9.32",
+    "@types/react-dom": "^16.9.6",
+    "babel-plugin-import": "^1.13.0",
+    "customize-cra": "^0.9.1",
+    "react-app-rewired": "^2.1.6",
+    "react-scripts": "^3.4.1",
+    "source-map-explorer": "^2.4.2"
+  },
+  "browserslist": {
+    "production": [
+      ">0.2%",
+      "not dead",
+      "not op_mini all"
+    ],
+    "development": [
+      "last 1 chrome version",
+      "last 1 firefox version",
+      "last 1 safari version"
+    ]
+  }
+}