be more explicit about our contributors

lib/book.sty

@@ -292,10 +292,17 @@
 \uppertitleback{
   {\bfseries Credits}
   \begin{description}
-  \item[Text] Jonathan S. Duff, Moritz Lenz, Carl Mäsak, Patrick R. Michaud, Jonathan Worthington with numerous contributions from the community.
+  \item[Text] Jonathan S. Duff, Moritz Lenz, Carl Mäsak, Patrick R. Michaud,
+      Jonathan Worthington.
   \item[Front cover] Sebastian Riedel (\url{http://kraih.com})
   \item[Fonts]Adobe Minion® Pro, Adobe Myriad® Pro, B\&H Luxi Mono
   \item[\LaTeX-Layout] Nikolai Prokoschenko, Luc St-Louis et al. Special thanks to Konrad Mühler for his \LaTeX\ tips collection (\url{http://www.kfiles.de/latex.php})
+  \item[Editor] chromatic
+  \item[Further text contributions] Bruce Gray, Matt Kraai, Gabor Szabo,
+      Hongwen Qiu, Alex Elsayed, Solomon Foster, Nuno Carvalho, Will Coleda,
+      Aaron Sherman, Prakash Kailasa, Carlin Bingham, Dean Serenevy,
+      Jason Felds, Piotr Fusik, Ralf Valerien, Tim Bunce, molecules
+      and snarkyboojum.
   \end{description}
 }
 \lowertitleback{