Update ocr_book.md

doc/doc_ch/ocr_book.md

@@ -20,7 +20,8 @@
 
 
 ## 资料地址
-- [教学视频与notebook教程](https://aistudio.baidu.com/aistudio/education/group/info/25207)
+- [notebook教程](https://github.com/PaddlePaddle/PaddleOCR/tree/dygraph/notebook/notebook_ch)
+- [教学视频与](https://aistudio.baidu.com/aistudio/education/group/info/25207)
 - 中文版电子书下载请扫描以下二维码入群后领取
 <div align="center">
 <img src="https://raw.githubusercontent.com/PaddlePaddle/PaddleOCR/dygraph/doc/joinus.PNG"  width = "200" height = "200" />