Update docstring

Author: rhshadrach

pandas/errors/__init__.py

@@ -668,7 +668,7 @@ class ChainedAssignmentError(Warning):
     """
     Warning raised when trying to set using chained assignment.
 
-    When the ``mode.copy_on_write`` option is enabled, chained assignment can
+    With Copy-on-Write now always enabled, chained assignment can
     never work. In such a situation, we are always setting into a temporary
     object that is the result of an indexing operation (getitem), which under
     Copy-on-Write always behaves as a copy. Thus, assigning through a chain
@@ -677,18 +677,11 @@ class ChainedAssignmentError(Warning):
     For more information on Copy-on-Write,
     see :ref:`the user guide<copy_on_write>`.
 
-    See Also
-    --------
-    options.mode.copy_on_write : Global setting for enabling or disabling
-        Copy-on-Write behavior.
-
     Examples
     --------
-    >>> pd.options.mode.copy_on_write = True
     >>> df = pd.DataFrame({"A": [1, 1, 1, 2, 2]}, columns=["A"])
     >>> df["A"][0:3] = 10  # doctest: +SKIP
     ... # ChainedAssignmentError: ...
-    >>> pd.options.mode.copy_on_write = False
     """