Fix error sed

README.md

 # 深度学习入门
 
-1. 新手入门 [[fit_a_line]](fit_a_line/) [[html](http://book.paddlepaddle.org/fit_a_line)]
-1. 识别数字 [[recognize_digits]](recognize_digits/) [[html](http://book.paddlepaddle.org/recognize_digits)]
-1. 图像分类 [[image_classification]](image_classification/) [[html](http://book.paddlepaddle.org/image_classification)]
-1. 词向量 [[word2vec]](word2vec/) [[html](http://book.paddlepaddle.org/word2vec)]
-1. 情感分析 [[understand_sentiment]](understand_sentiment/) [[html](http://book.paddlepaddle.org/understand_sentiment)]
-1. 语义角色标注 [[label_semantic_roles]](label_semantic_roles/) [[html](http://book.paddlepaddle.org/label_semantic_roles)]
-1. 机器翻译 [[machine_translation]](machine_translation/) [[html](http://book.paddlepaddle.org/machine_translation)]
-1. 个性化推荐 [[recommender_system]](recommender_system/) [[html](http://book.paddlepaddle.org/recommender_system)]
+1. 新手入门 [[fit_a_line](fit_a_line/)] [[html](http://book.paddlepaddle.org/fit_a_line)]
+1. 识别数字 [[recognize_digits](recognize_digits/)] [[html](http://book.paddlepaddle.org/recognize_digits)]
+1. 图像分类 [[image_classification](image_classification/)] [[html](http://book.paddlepaddle.org/image_classification)]
+1. 词向量 [[word2vec](word2vec/)] [[html](http://book.paddlepaddle.org/word2vec)]
+1. 情感分析 [[understand_sentiment](understand_sentiment/)] [[html](http://book.paddlepaddle.org/understand_sentiment)]
+1. 语义角色标注 [[label_semantic_roles](label_semantic_roles/)] [[html](http://book.paddlepaddle.org/label_semantic_roles)]
+1. 机器翻译 [[machine_translation](machine_translation/)] [[html](http://book.paddlepaddle.org/machine_translation)]
+1. 个性化推荐 [[recommender_system](recommender_system/)] [[html](http://book.paddlepaddle.org/recommender_system)]
 
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 <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/"><img alt="知识共享许可协议" style="border-width:0" src="https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png" /></a><br /><span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Text" property="dct:title" rel="dct:type">本教程</span> 由 <a xmlns:cc="http://creativecommons.org/ns#" href="http://book.paddlepaddle.org" property="cc:attributionName" rel="cc:attributionURL">PaddlePaddle</a> 创作，采用 <a rel="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">知识共享 署名-非商业性使用-相同方式共享 4.0 国际 许可协议</a>进行许可。