fix indent bugs

fit_a_line/README.md

@@ -125,17 +125,13 @@ def main():
 
 ```python
     #输入数据，13维的房屋信息
-	x = paddle.layer.data(name='x',
-	                type=paddle.data_type.dense_vector(13))
-	
+    x = paddle.layer.data(name='x', type=paddle.data_type.dense_vector(13))
     y_predict = paddle.layer.fc(input=x,
                                 param_attr=paddle.attr.Param(name='w'),
                                 size=1,
                                 act=paddle.activation.Linear(),
                                 bias_attr=paddle.attr.Param(name='b'))
-	                            
-	y = paddle.layer.data(name='y',
-	            type=paddle.data_type.dense_vector(1))
+    y = paddle.layer.data(name='y', type=paddle.data_type.dense_vector(1))
     cost = paddle.layer.regression_cost(input=y_predict, label=y)
 ```
 ### 接着创建参数和优化器