!19703 Add Example for shard and set_stage API

Merge pull request !19703 from huangxinjing/code_docs_fix_doc

mindspore/nn/wrap/grad_reducer.py

@@ -291,7 +291,7 @@ class DistributedGradReducer(Cell):
         ValueError: If degree is not a int or less than 0.
 
     Supported Platforms:
-        ``Ascend``, ``GPU``
+        ``Ascend`` ``GPU``
 
     Examples:
         >>> # This example should be run with multiple processes.

mindspore/ops/primitive.py

@@ -140,9 +140,13 @@ class Primitive(Primitive_):
         Note:
             It is valid only in semi auto parallel.
             In other parallel modes, please set it to be 0.
-
         Args:
             stage (int): The stage id for the current operation.
+        Example:
+        >>> from mindspore.ops import operations as P
+        >>> add = P.Add()
+        >>> print(add.set_stage(0))
+        Prim[Add]<stage=0>
         """
         self.add_prim_attr("stage", stage)
         return self
@@ -157,6 +161,11 @@ class Primitive(Primitive_):
 
         Args:
             strategy (tuple): Strategy describes the distributed parallel mode of the current primitive.
+        Example:
+        >>> from mindspore.ops import operations as P
+        >>> add = P.Add()
+        >>> print(add.shard(((1, 1), (1, 1))))
+        Prim[Add]<strategy=((1, 1), (1, 1))>
         """
         mode = context.get_auto_parallel_context("parallel_mode")
         if strategy is not None: