修改COPY-FROM No. 2 jit (#54920)

* [jit] add copy-from; test=document_fix

* [jit] add copy-from; test=document_fix

* fix TracedLayer

python/paddle/jit/api.py

@@ -1308,6 +1308,7 @@ def load(path, **configs):
         1. Load model saved by ``paddle.jit.save`` then performing inference and fine-tune training.
 
         .. code-block:: python
+            :name: code-example1
 
             import numpy as np
             import paddle
@@ -1395,6 +1396,7 @@ def load(path, **configs):
         2. Load model saved by ``paddle.fluid.io.save_inference_model`` then performing and fine-tune training.
 
         .. code-block:: python
+            :name: code-example2
 
             import numpy as np
             import paddle
@@ -1608,7 +1610,7 @@ class TracedLayer:
                 TracedLayer object.
 
         Examples:
-            .. code-block:: python:
+            .. code-block:: python
 
                 import paddle
 
@@ -1658,7 +1660,7 @@ class TracedLayer:
             None
 
         Examples:
-            .. code-block:: python:
+            .. code-block:: python
 
                 import paddle
 
@@ -1761,7 +1763,7 @@ class TracedLayer:
             None
 
         Examples:
-            .. code-block:: python:
+            .. code-block:: python
 
                 import numpy as np
                 import paddle