update doc

doc/doc_ch/training.md

@@ -129,3 +129,9 @@ PaddleOCR主要聚焦通用OCR，如果有垂类需求，您可以用PaddleOCR+
 
     A：识别模型训练初期acc为0是正常的，多训一段时间指标就上来了。
 
+
+***
+具体的训练教程可点击下方链接跳转：  
+- [文本检测模型训练](https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_ch/detection.md)  
+- [文本识别模型训练](https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_ch/recognition.md)  
+- [文本方向分类器训练](https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_ch/angle_class.md)  
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doc/doc_en/training_en.md

@@ -147,3 +147,9 @@ There are several experiences for reference when constructing the data set:
 
     A: It is normal for the acc to be 0 at the beginning of the recognition model training, and the indicator will come up after a longer training period.
 
+
+***
+Click the following links for detailed training tutorial:  
+- [text detection model training](https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_ch/detection.md)  
+- [text recognition model training](https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_ch/recognition.md)  
+- [text direction classification model training](https://github.com/PaddlePaddle/PaddleOCR/blob/release/2.3/doc/doc_ch/angle_class.md)