gh-142020: ctypes docs: Note that find_library relies on the programs it runs (GH-142134)

Author: encukou

Doc/library/ctypes.rst

@@ -1388,6 +1388,9 @@ On Linux, :func:`~ctypes.util.find_library` tries to run external programs
 (``/sbin/ldconfig``, ``gcc``, ``objdump`` and ``ld``) to find the library file.
 It returns the filename of the library file.
 
+Note that if the output of these programs does not correspond to the dynamic
+linker used by Python, the result of this function may be misleading.
+
 .. versionchanged:: 3.6
    On Linux, the value of the environment variable ``LD_LIBRARY_PATH`` is used
    when searching for libraries, if a library cannot be found by any other means.
@@ -2132,6 +2135,8 @@ Utility functions
 
    The exact functionality is system dependent.
 
+   See :ref:`ctypes-finding-shared-libraries` for complete documentation.
+
 
 .. function:: find_msvcrt()
    :module: ctypes.util