[book] add autoload section from code and fix sphinx warnings * drop misleading faq entry since clear explanation can be found in internationalization chapter * use autodata sphinx directive instead of raw text * fill empty chapter with autodoc: - devweb/httpcaching.rst - devweb/resource.rst - devweb/views/idownloadable.rst - devweb/views/wdoc.rst * use shebang in excerpt to denote shell code * fix some bad indented docstrings in javascript files

doc/book usr/share/doc/cubicweb-documentation
doc/html usr/share/doc/cubicweb-documentation
debian/cubicweb-doc usr/share/doc-base/cubicweb-doc