[3.10] gh-94635: Frame sqlite3 how-to headings as such & move default adapters to reference (GH-96136) (#96227)

Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>
Co-authored-by: Ezio Melotti <ezio.melotti@gmail.com>.
(cherry picked from commit 6bda5b85b53443f3467865fbf85cbe72932e7cd6)

Co-authored-by: C.A.M. Gerlach <CAM.Gerlach@Gerlach.CAM>