Guidebook.mn SPECIAL THANKS - no need to shout

Guidebook.tex already uses mixed case for "Special Thanks"
but it put Dungeoneers into a new section--one on par with
Credits--rather than have that be a continuation of the
Special Thanks subsection.  Split the difference:  make
Dungeoneers be a second subsection of Credits in both.

doc/Guidebook.tex

@@ -6688,13 +6688,14 @@ unnamed dungeoneers who invest their time and effort into annual
 {\it devnull.net\/} (gone for now, but not forgotten).
 \clearpage
 
-%.hn
-\section*{Dungeoneers}
+%.hn 2
+\subsection*{Dungeoneers}
 %.pg
 \nd From time to time, some depraved individual out there in netland sends a
 particularly intriguing modification to help out with the game.  The
 {\it NetHack Development Team} sometimes makes note of the names of the worst
 of these miscreants in this, the list of Dungeoneers:
+\medskip
 %.sd
 \begin{center}
 \begin{tabular}{llll}