!49909 fix Transformer docs

Merge pull request !49909 from 吕昱峰（Nate.River）/code_docs_master

mindspore/python/mindspore/nn/layer/transformer.py

@@ -123,9 +123,15 @@ class MultiheadAttention(Cell):
         ``Ascend`` ``GPU`` ``CPU``
 
     Examples:
+        >>> embed_dim, num_heads = 128, 8
+        >>> seq_length, batch_size = 10, 8
+        >>> query = Tensor(np.random.randn(seq_length, batch_size, embed_dim), mindspore.float32)
+        >>> key = Tensor(np.random.randn(seq_length, batch_size, embed_dim), mindspore.float32)
+        >>> value = Tensor(np.random.randn(seq_length, batch_size, embed_dim), mindspore.float32)
         >>> multihead_attn = nn.MultiheadAttention(embed_dim, num_heads)
         >>> attn_output, attn_output_weights = multihead_attn(query, key, value)
-
+        >>> print(attn_output.shape)
+        (10, 8, 128)
     """
 
     def __init__(self, embed_dim, num_heads, dropout=0., has_bias=True, add_bias_kv=False,
@@ -267,6 +273,8 @@ class TransformerEncoderLayer(Cell):
         >>> encoder_layer = nn.TransformerEncoderLayer(d_model=512, nhead=8, batch_first=True)
         >>> src = Tensor(np.random.rand(32, 10, 512), mindspore.float32)
         >>> out = encoder_layer(src)
+        >>> print(out.shape)
+        (32, 10, 512)
     """
     __constants__ = ['batch_first', 'norm_first']
 
@@ -378,6 +386,8 @@ class TransformerDecoderLayer(Cell):
         >>> memory = Tensor(np.random.rand(32, 10, 512), mindspore.float32)
         >>> tgt = Tensor(np.random.rand(32, 20, 512), mindspore.float32)
         >>> out = decoder_layer(tgt, memory)
+        >>> print(out.shape)
+        (32, 20, 512)
     """
     __constants__ = ['batch_first', 'norm_first']
 
@@ -479,6 +489,8 @@ class TransformerEncoder(Cell):
         >>> transformer_encoder = nn.TransformerEncoder(encoder_layer, num_layers=6)
         >>> src = Tensor(np.random.rand(10, 32, 512), mindspore.float32)
         >>> out = transformer_encoder(src)
+        >>> print(out.shape)
+        (10, 32, 512)
     """
     __constants__ = ['norm']
 
@@ -537,6 +549,8 @@ class TransformerDecoder(Cell):
         >>> memory = Tensor(np.random.rand(10, 32, 512), mindspore.float32)
         >>> tgt = Tensor(np.random.rand(20, 32, 512), mindspore.float32)
         >>> out = transformer_decoder(tgt, memory)
+        >>> print(out.shape)
+        (20, 32, 512)
     """
     __constants__ = ['norm']
 
@@ -604,11 +618,16 @@ class Transformer(Cell):
     Outputs:
         Tensor.
 
+    Supported Platforms:
+        ``Ascend`` ``GPU`` ``CPU``
+
     Examples:
         >>> transformer_model = nn.Transformer(nhead=16, num_encoder_layers=12)
         >>> src = Tensor(np.random.rand(10, 32, 512), mindspore.float32)
         >>> tgt = Tensor(np.random.rand(20, 32, 512), mindspore.float32)
         >>> out = transformer_model(src, tgt)
+        >>> print(out.shape)
+        (20, 32, 512)
     """
 
     def __init__(self, d_model: int = 512, nhead: int = 8, num_encoder_layers: int = 6,