[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

[theme]
inherit = pyramid
pygments_style = sphinx.pygments_styles.PyramidStyle
stylesheet = cubicweb.css


[options]
logo = logo-cubicweb.svg
favicon = cubicweb.ico
in_progress = false
outdated = false
canonical_url =