[doc] Link to section File input (GH-28941) (GH-29376)

(cherry picked from commit 48824fa)

Co-authored-by: Andre Delfino <[email protected]>

Author: miss-islington

Doc/library/functions.rst

@@ -507,7 +507,7 @@ are always available.  They are listed here in alphabetical order.
    a suite of Python statements which is then executed (unless a syntax error
    occurs). [#]_ If it is a code object, it is simply executed.  In all cases,
    the code that's executed is expected to be valid as file input (see the
-   section "File input" in the Reference Manual). Be aware that the
+   section :ref:`file-input` in the Reference Manual). Be aware that the
    :keyword:`nonlocal`, :keyword:`yield`,  and :keyword:`return`
    statements may not be used outside of
    function definitions even within the context of code passed to the