doc (components): update AP component documentation: - add `configuration` section - update instructions on AP actor handle <=> JID/node conversion - explain how to get AP messages from XMPP - explain how to get XMPP items for AP - notes to explain tricks and implementations details fix 363

You'll find install instructions in documentation (see doc/installation.rst).

If you need help, come the SàT official XMPP room: sat@chat.jabberfr.org or join us with a web browser via https://chat.jabberfr.org/converse.js/sat@chat.jabberfr.org