Update storybook directory

Author: codejs-kr

frontend/src/components/common/Avatar/Avatar.stories.js renamed to frontend/stories/Avatar.stories.js

@@ -1,5 +1,5 @@
 import React from 'react';
-import Avatar from './Avatar';
+import Avatar from '../src/components/common/Avatar';
 
 export default {
   title: 'components|common/Avatar',

frontend/src/components/layout/Iphone/Iphone.stories.js renamed to frontend/stories/Iphone.stories.js

@@ -1,5 +1,5 @@
 import React from 'react';
-import Iphone from './Iphone';
+import Iphone from '../src/components/layout/Iphone';
 
 export default {
   title: 'components|layout/Iphone', // 스토리북에서 보여질 그룹과 경로를 명시