Update example

Author: jarvelov

docs/api/ui-schema.md

@@ -2,14 +2,36 @@
 
 An array of [fields](ui-schema/field.md).
 
+## Example
+
 ```js
   data() {
     return {
-      uiSchema: [{
-        component: 'div'
-      }, {
-        component: MyCustomComponent,
-      }]
+      uiSchema: [
+        {
+          component: 'div',
+          fieldOptions: {
+            class: ['form-group']
+          },
+          children: [
+            {
+              component: 'input',
+              model: 'firstName',
+              fieldOptions: {
+                on: ['input']
+              }
+            }
+          ]
+        }
+      ]
     }
   }
 ```
+
+The example above will do essentially the same thing as the following Vue template:
+
+```html
+<div class="form-group">
+  <input v-model="model.firstName" />
+</div>
+```