C API doc: try to group concrete objects
diff --git a/Doc/c-api/concrete.rst b/Doc/c-api/concrete.rst
index 65904ee..2d56386 100644
--- a/Doc/c-api/concrete.rst
+++ b/Doc/c-api/concrete.rst
@@ -74,26 +74,35 @@
 
 .. _mapobjects:
 
-Mapping Objects
-===============
+Container Objects
+=================
 
 .. index:: object: mapping
 
 .. toctree::
 
    dict.rst
+   set.rst
 
 
 .. _otherobjects:
 
+Function Objects
+================
+
+.. toctree::
+
+   function.rst
+   method.rst
+   cell.rst
+   code.rst
+
+
 Other Objects
 =============
 
 .. toctree::
 
-   set.rst
-   function.rst
-   method.rst
    file.rst
    module.rst
    iterator.rst
@@ -102,7 +111,6 @@
    memoryview.rst
    weakref.rst
    capsule.rst
-   cell.rst
    gen.rst
    datetime.rst
-   code.rst
+