[3.11] Fix a code snippet typo in asyncio docs (GH-108427) (#111244)

Co-authored-by: A <5249513+Dumeng@users.noreply.github.com>

Doc/library/asyncio-task.rst

@@ -539,7 +539,7 @@ Shielding From Cancellation
 
    is equivalent to::
 
-       res = await something()
+       res = await shield(something())
 
    *except* that if the coroutine containing it is cancelled, the
    Task running in ``something()`` is not cancelled.  From the point