Change script command from serve to playground

Author: bidoubiwa

package.json

@@ -4,7 +4,7 @@
   "description": "Relevant and typo tolerant search bar for your Vuepress",
   "author": "Clémentine Urquizar <[email protected]>",
   "scripts": {
-    "serve": "yarn --cwd ./playground install && yarn --cwd ./playground dev",
+    "playground": "yarn --cwd ./playground install && yarn --cwd ./playground dev",
     "lint": "eslint '{.,tests}/**/*.{vue,js}'",
     "lint:fix": "yarn lint --fix",
     "test": "vue-cli-service test:unit"