hgame.4: Polish

Explain driver loading and application access in the body of the manual.
Crossreference other game controller driver manuals, and devfs.rules to
hint about how to configure application access. Add a common dongle to
supported hardware. Add evdev a few places to make it really clear how
it works.

MFC after: immediately for inclusion in 15.0R
Reviewed by: wulf
Differential Revision: https://reviews.freebsd.org/D53290

(cherry picked from commit c0c8d812b560a3e89656c026022a44631f88e233)