User's Guide: more init info, autoprobing, etc

Mention the autoprobing as a tool that may be useful when
figuring out how to set up; and add a section showing how
to use that mechanism (with an example).

Strengthen the differences between config and run stage
descriptions; add a section for the latter.

Mention Dragonite.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>