Merge pull request #66 from xiaoye-hua/bug_fix

更正7.3的笔误

Author: archersama

docs/chapter07_optimization/7.3_minibatch-sgd.md

@@ -179,7 +179,7 @@ def train_tensorflow2_ch7(trainer_name, trainer_hyperparams, features, labels,
 ```
 使用Tensorflow2重复上一个实验。
 ``` python
-train_pytorch_ch7(optim.SGD, {"lr": 0.05}, features, labels, 10)
+train_tensorflow2_ch7('trainer', {'learning_rate': 0.05}, features, labels, 10)
 ```
 输出：
 ```