Add index for classes ref

classes/index.rst

@@ -0,0 +1,9 @@
+Classes reference
+=================
+
+.. toctree::
+   :maxdepth: 1
+   :name: class-ref
+   :glob:
+
+   class_*

contributing/index.rst

@@ -9,4 +9,5 @@ Contributing
    documentation_guidelines
    documentation_writing_and_translating_guidelines
    list_of_classes_and_documenters
+   reference_filling_work
    wiki_syntax

index.rst

@@ -14,6 +14,7 @@ The main documentation for the site is organized into a couple sections:
    :maxdepth: 1
    :caption: User documentation
    :name: user-doc
+   :hidden:
 
    tutorials/basic
    tutorials/engine
@@ -28,7 +29,6 @@ The main documentation for the site is organized into a couple sections:
    advanced/index
    contributing/index
 
-
 .. Indices and tables
 .. ------------------
 .. 

reference/index.rst

@@ -5,6 +5,6 @@ Reference
    :maxdepth: 2
    :name: reference
 
-   reference_filling_work
+   ../classes/index
    languages
    cheat_sheets