[doc] Update "settings" pyramid documentation Document that without "bwcompat" we can use a development.ini file directly and add a dedicated section to list configuration options.

[doc] Update the "quickstart" page of pyramid documentation Again mentioning the two modes of operations and dropping references to prior implementation.

[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).