[3.13] fix indent in controlflow.rst docs (GH-134008) (#134185)

fix indent in `controlflow.rst` docs (GH-134008)
(cherry picked from commit 4ce9187)

Co-authored-by: Yongzi Li <1538321957@qq.com>

Author: miss-islington

Doc/tutorial/controlflow.rst

@@ -1055,7 +1055,7 @@ Here is an example of a multi-line docstring::
    >>> print(my_function.__doc__)
    Do nothing, but document it.
 
-       No, really, it doesn't do anything.
+   No, really, it doesn't do anything.
 
 
 .. _tut-annotations: