📝 Update Knobs addon documentation for Ember (#8977)

📝 Update Knobs addon documentation for Ember

addons/knobs/README.md

@@ -128,7 +128,29 @@ stories.add('with a button', () => ({
    text: text('text', 'Hello Storybook'), // The first param of the knob function has to be exactly the same as the component input.
   },
 }));
+```
 
+### With Ember
+```js
+import { withKnobs, text, boolean } from '@storybook/addon-knobs';
+import hbs from 'htmlbars-inline-precompile';
+
+export default {
+  title: 'StoryBook with Knobs',
+  decorators: [withKnobs],
+};
+
+export const button = () => {
+  return {
+    template: hbs`
+    <button disabled={{disabled}}>{{label}}</button>
+    `,
+    context: {
+      label: text('label', 'Hello Storybook'),
+      disabled: boolean('disabled', false),
+    },
+  };
+};
 ```
 
 Categorize your Knobs by assigning them a `groupId`. When a `groupId` exists, tabs will appear in the Knobs storybook panel to filter between the groups. Knobs without a `groupId` are automatically categorized into the `ALL` group.