docs: note rule non-persistence in Tutorial-04 and Tutorial-11 Rules are session-scoped (in-memory only). Added a bullet to Tutorial-04's key concepts section and a session note in Tutorial-11 before the customer-of-seller rule definition.
Replaced clojure fences with datalog.
docs: add query label to recursive rule section in Section 11
docs: add recursive rule to Section 11 marketplace
docs: tutorial section 11 — marketplace