fix the diff of sample code in chinese doc with english doc (#2038)

fix the diff of sample code in chinese doc with english doc

doc/fluid/api_cn/dygraph_cn/load_dygraph_cn.rst

@@ -32,7 +32,8 @@ load_dygraph
         emb = fluid.dygraph.Embedding([10, 10])
         state_dict = emb.state_dict()
         fluid.save_dygraph( state_dict, "paddle_dy")
-        adam = fluid.optimizer.Adam( learning_rate = fluid.layers.noam_decay( 100, 10000) )
+        adam = fluid.optimizer.Adam( learning_rate = fluid.layers.noam_decay( 100, 10000) ,
+                                     parameter_list = emb.parameters() )
         state_dict = adam.state_dict()
         fluid.save_dygraph( state_dict, "paddle_dy")
 

doc/fluid/api_cn/dygraph_cn/save_dygraph_cn.rst

@@ -29,15 +29,13 @@ save_dygraph
     import paddle.fluid as fluid
 
     with fluid.dygraph.guard():
-        emb = fluid.dygraph.Embedding(
-            size=[10, 32],
-            param_attr='emb.w',
-            is_sparse=False)
+        emb = fluid.dygraph.Embedding([10, 10])
+
         state_dict = emb.state_dict()
-        fluid.save_dygraph(state_dict, "paddle_dy")  # 会保存为 paddle_dy.pdparams
+        fluid.save_dygraph( state_dict, "paddle_dy") # 会保存为 paddle_dy.pdparams
+
+        adam = fluid.optimizer.Adam( learning_rate = fluid.layers.noam_decay( 100, 10000),
+                                     parameter_list = emb.parameters() )
 
-        adam = fluid.optimizer.Adam(
-            learning_rate=fluid.layers.noam_decay(100, 10000),
-            parameter_list = emb.parameters())
         state_dict = adam.state_dict()
-        fluid.save_dygraph(state_dict, "paddle_dy")  # 会保存为 paddle_dy.pdopt
+        fluid.save_dygraph( state_dict, "paddle_dy") # 会保存为 paddle_dy.pdopt
\ No newline at end of file

doc/fluid/api_cn/fluid_cn/in_dygraph_mode_cn.rst

@@ -16,11 +16,11 @@ in_dygraph_mode
 
 .. code-block:: python
 
-    from __future__ import print_function
     import paddle.fluid as fluid
-    if fluid.in_dygraph_mode():
-        print('running in dygraph mode')
-    else:
-        print('not running in dygraph mode')
+
+    fluid.enable_dygraph()          # 现在进入 dygragh 模式
+    print(fluid.in_dygraph_mode())  # True
+    fluid.disable_dygraph()
+    print(fluid.in_dygraph_mode())  # False