update nodemon watch configuration to restart dev-server when new entry points are added

package.json

 {
   "private": true,
   "scripts": {
-    "dev-server": "nodemon --watch config/webpack.config.js -- ./node_modules/.bin/webpack-dev-server --config config/webpack.config.js",
+    "dev-server": "nodemon -w 'config/webpack.config.js' -w 'app/assets/javascripts/dispatcher.js' -w 'app/assets/javascripts/pages/**/index.js' --exec 'webpack-dev-server --config config/webpack.config.js'",
     "eslint": "eslint --max-warnings 0 --ext .js,.vue .",
     "eslint-fix": "eslint --max-warnings 0 --ext .js,.vue --fix .",
     "eslint-report": "eslint --max-warnings 0 --ext .js,.vue --format html --output-file ./eslint-report.html .",