added a first idea of what could be the API

CONTRIBUTING.md

@@ -13,4 +13,5 @@ the
 [style guide](https://docs.godotengine.org/en/latest/getting_started/\scripting/gdscript/gdscript_styleguide.html)
 described in Godot Documentation.
 
+When creating a class or a function, describe it in the API chapter of the documentation
 The API follows the same style as [Godot API](https://docs.godotengine.org/en/latest/classes/index.html)

docs/sphinx/source/api/class-sign-symb.rst

+.. _SignSymb:
+
+==========
+ SignSymb
+==========
+
+.. warning::
+
+   For the moment, SignSymb is only a dummy text display that is used to test
+   the :ref:`WorkSpace`
+

docs/sphinx/source/api/class-work-space.rst

+.. _WorkSpace:
+
+===========
+ WorkSpace
+===========
+
+Inherits from the Container class.
+
+-----------------
+Brief Description
+-----------------
+
+Container used to prompt the speech in a text-editor way.
+
+----------
+Properties
+----------
+
+.. _class_WorkSpace_prop_sep:
+
+ * Vector2 **sep**
+
+   The sizes in pixel of the horizontal and vertical separators between two
+   words.
+
+.. _class_WorkSpace_prop_text:
+
+ * Array **text**
+
+   The signs of the speech in a big "string".

docs/sphinx/source/api/index.rst

 ==============
  Software API
 ==============
+
+.. toctree::
+   :maxdepth: 1
+   :glob:
+
+   class-*
+
+