Comment: float32 => float16; test=docoument_fix (#50156)

test=docoument_fix

python/paddle/amp/auto_cast.py

@@ -700,7 +700,7 @@ def auto_cast(
 
         with paddle.amp.auto_cast():
             conv = conv2d(data)
-            print(conv.dtype) # paddle.float32
+            print(conv.dtype) # paddle.float16
 
         with paddle.amp.auto_cast(enable=False):
             conv = conv2d(data)
@@ -714,11 +714,11 @@ def auto_cast(
         b = paddle.rand([2,3])
         with paddle.amp.auto_cast(custom_white_list={'elementwise_add'}):
             c = a + b
-            print(c.dtype) # paddle.float32
+            print(c.dtype) # paddle.float16
 
         with paddle.amp.auto_cast(custom_white_list={'elementwise_add'}, level='O2'):
             d = a + b
-            print(d.dtype) # paddle.float32
+            print(d.dtype) # paddle.float16
 
     """
     return amp_guard(enable, custom_white_list, custom_black_list, level, dtype)