Change development scripts

Switch to npm-workspaces monorepo task management.

packages/benchmarks/README.md

@@ -2,20 +2,14 @@
 
 Try the [benchmarks app](https://necolas.github.io/react-native-web/benchmarks) online.
 
-To run the benchmarks locally from monorepo root:
+To work on the benchmarks locally from monorepo root:
 
 ```
-yarn benchmarks
+npm run dev -w react-native-web
+npm run build -w benchmarks
 open ./packages/benchmarks/dist/index.html
 ```
 
-Develop against these benchmarks from monorepo root:
-
-```
-yarn compile --watch
-yarn benchmarks --watch
-```
-
 ## Notes
 
 These benchmarks are approximations of extreme cases that libraries may

packages/benchmarks/package.json

@@ -3,8 +3,9 @@
   "name": "benchmarks",
   "version": "0.0.0",
   "scripts": {
-    "dev": "mkdir -p dist && cp -f index.html dist/index.html && ./node_modules/.bin/webpack-cli --config ./webpack.config.js",
-    "build": "NODE_ENV=production yarn dev"
+    "clean": "del-cli ./dist",
+    "build": "NODE_ENV=production npm run dev",
+    "dev": "npm run clean && mkdir -p dist && cp -f index.html dist/index.html && ./node_modules/.bin/webpack-cli --config ./webpack.config.js"
   },
   "dependencies": {
     "classnames": "^2.3.1",