refactor: lint all js blocks in markdown files (nuxt#1681)

Author: pi0

.eslintrc

@@ -0,0 +1,13 @@
+{
+  "root": true,
+  "parserOptions": {
+    "parser": "babel-eslint",
+    "sourceType": "module"
+  },
+  "extends": [
+    "@nuxtjs"
+  ],
+  "plugins": [
+    "markdown"
+  ]
+}

de/api/components-nuxt.md

@@ -43,9 +43,9 @@ There are 3 ways to handle internal `key` prop of `<router-view/>`.
 
   ```js
   export default {
-     key(route) {
-       return route.fullPath
-     }
+    key (route) {
+      return route.fullPath
+    }
   }
   ```