[doc] Rewrite "pyramid" index page in the book We drop references to pyramid-cubicweb and cubicweb-pyramid, remaining of the merge in 3.24. We now mention the two possible operation modes (with bwcompat being true or false).

missing-dep-for-interpreter make => make | build-essential | dpkg-dev (usr/*/cubicweb/skeleton/debian/rules)
embedded-javascript-library usr/share/cubicweb/cubes/shared/data/jquery.js