Add Chinese doc and language switcher for demos of metaverse, style_fs2 and story talker, test=doc

demos/story_talker/README.md

+([简体中文](./README_cn.md)|English)
+
 # Story Talker
 ## Introduction
 Storybooks are very important children's enlightenment books, but parents usually don't have enough time to read storybooks for their children. For very young children, they may not understand the Chinese characters in storybooks. Or sometimes, children just want to "listen" but don't want to "read".

demos/story_talker/README_cn.md

+
+(简体中文|[English](./README.md))
+
+# Story Talker
+
+## 简介
+
+故事书是非常重要的儿童启蒙书，但家长通常没有足够的时间为孩子读故事书。对于非常小的孩子，他们可能不理解故事书中的汉字。或有时，孩子们只是想“听”，而不想“读”。
+
+您可以使用`PaddleOCR` 获取故事书的文本，并通过`PaddleSpeech`的 `TTS` 模块进行阅读。
+
+## 使用
+
+运行以下命令行开始：
+
+```
+./run.sh
+```
+
+结果已显示在 [notebook](https://github.com/PaddlePaddle/PaddleSpeech/blob/develop/docs/tutorial/tts/tts_tutorial.ipynb)。