docs(options): update appContext for file import

Author: ThornWalli

docs/content/1.v2/1.guide/1.options.md

@@ -159,10 +159,21 @@ Return value is the `config`. `async` is supported.
 | `async`       | `Boolean`            |          | Components are loaded asynchronously. If there is more than one entry the async will lead to unwanted webpack chunk splitting.           | `false`     |
 | `path`        | `String`             |          | Path to the component to be called by the tag.                                                                                           | `false`     |
 | `options`     | `Function`, `Object` |          | Options from custom-element. <br>[Learn more](https://github.com/karol-f/vue-custom-element#options) about `vue-custom-element` options. | `undefined` |
-| `appContext`  | `Function`           |          | Function call to extend the Vue app. Example: Plugin registration of `vuetify`, `pinia`, `vue-router`, ...                               | `undefined` |
+| `appContext`  | `String`, `Function` |          | File Reference or Function call to extend the Vue app. Example: Plugin registration of `vuetify`, `pinia`, `vue-router`, ...             | `undefined` |
 | `css`         | `String`             |          | Can be used to inject CSS into the element.                                                                                              | `undefined` |
 | `slotContent` | `String`             |          | Default slot content for generated html entry output.                                                                                    | `undefined` |
 
+#### Example appContext config file
+
+```js
+export default function (Vue) {
+  // Customize Vue App here
+  // e.g. Vue.component('my-component', MyComponent) or Vue.use(MyPlugin)
+
+  console.log('Vue App', Vue);
+}
+```
+
 #### Important
 
 1. You can set as `object` or when using functions in options, use `function`.
@@ -200,12 +211,28 @@ Return value is the `config`. `async` is supported.
 }
 ```
 
-2. You can extend the Vue app to install plugins, for example. (e.g. `vuetify`, `pinia`, `vue-18n`, `vue-router`)
+2. You can customize the Vue app to install plugins, for example. (e.g. `vuetify`, `pinia`, `vue-18n`, `vue-router`)
 
 ```js
 {
   name: 'ComponentAppExample',
   tags: [
+    // Recommended to control appContext via config file.
+    {
+      async: true,
+      name: 'CustomElementAppExample',
+      path: '@/components/apps/AppExample',
+      options: {
+        props: {
+          'prop1': 'Value 1',
+          'prop2': 'Value 2'
+        }
+      },
+      appContext: '@/components/apps/AppExample.appContext.js',
+      slotContent: '<div>Slot Content!</div>'
+    },
+    // appContext can also be defined by function, this is copied to the entry by stringify. 
+    // Beware: function loses the scope to `nuxt.config`.
     {
       async: true,
       name: 'CustomElementAppExample',
@@ -246,10 +273,7 @@ Return value is the `config`. `async` is supported.
             options: {
               props: ['prop1', 'prop2'],
             },
-            appContext(Vue) {
-              console.log('Vue App', Vue);
-              // usage for Vue.use…
-            }
+            appContext: 'Path to ComponentOne Config',
           }
         ]
       },
@@ -264,7 +288,8 @@ Return value is the `config`. `async` is supported.
                 'prop1': 'Value 1',
                 'prop2': 'Value 2'
               }
-            }
+            },
+            appContext: 'Path to ComponentTwo Config',
           }
         ]
       },
@@ -279,7 +304,8 @@ Return value is the `config`. `async` is supported.
             path: 'Path to ComponentOne',
             options: {
               props: ['prop1', 'prop2']
-            }
+            },
+            appContext: 'Path to ComponentOne Config',
           },
           {
             async: true,