[doc] Restructure the documentation * Create a new index file * Move the sphinx configuration files do the documentation root * Move book/README to dev/documenting.rst * Move book/mode_plan.py to tools/ * Move book/en/images to images * Move book/en/* to book/ * Move changelogs to changes/* * Adapt the Makefile * Add a title to the javascript api index Related to #4832808

Cubes
=====

This chapter describes how to define your own cubes and reuse already available cubes.

.. toctree::
   :maxdepth: 1

   layout.rst
   cc-newcube.rst
   available-cubes.rst