bpo-36763, doc: Add links in the new C API init doc (GH-15433)

Author: vstinner

Doc/c-api/init.rst

@@ -7,6 +7,8 @@
 Initialization, Finalization, and Threads
 *****************************************
 
+See also :ref:`Python Initialization Configuration <init-config>`.
+
 .. _pre-init-safe:
 
 Before Python Initialization

Doc/c-api/init_config.rst

@@ -48,6 +48,8 @@ The preconfiguration (``PyPreConfig`` type) is stored in
 ``_PyRuntime.preconfig`` and the configuration (``PyConfig`` type) is stored in
 ``PyInterpreterState.config``.
 
+See also :ref:`Initialization, Finalization, and Threads <initialization>`.
+
 .. seealso::
    :pep:`587` "Python Initialization Configuration".