fix docs of auto_cast, cuda_places, static.save (#42107)

* auto_cast; test=document_fix

* static.save; test=document_fix

* cuda_places; test=document_fix

python/paddle/amp/auto_cast.py

@@ -54,25 +54,25 @@ def auto_cast(enable=True,
 
         with paddle.amp.auto_cast():
             conv = conv2d(data)
-            print(conv.dtype) # FP16
+            print(conv.dtype) # paddle.float32
 
         with paddle.amp.auto_cast(enable=False):
             conv = conv2d(data)
-            print(conv.dtype) # FP32
+            print(conv.dtype) # paddle.float32
 
         with paddle.amp.auto_cast(custom_black_list={'conv2d'}):
             conv = conv2d(data)
-            print(conv.dtype) # FP32
+            print(conv.dtype) # paddle.float32
 
         a = paddle.rand([2,3])
         b = paddle.rand([2,3])
         with paddle.amp.auto_cast(custom_white_list={'elementwise_add'}):
             c = a + b
-            print(c.dtype) # FP16
+            print(c.dtype) # paddle.float32
         
         with paddle.amp.auto_cast(custom_white_list={'elementwise_add'}, level='O2'):
             d = a + b
-            print(d.dtype) # FP16
+            print(d.dtype) # paddle.float32
 
     """
     return amp_guard(enable, custom_white_list, custom_black_list, level, dtype)

python/paddle/fluid/io.py

@@ -1846,8 +1846,7 @@ def _legacy_save(param_dict, model_path, protocol=2):
 @static_only
 def save(program, model_path, protocol=4, **configs):
     """
-    :api_attr: Static Graph
-
+    
     This function save parameters, optimizer information and network description to model_path.
 
     The parameters contains all the trainable Tensor, will save to a file with suffix ".pdparams".