Tweaks to CONTRIBUTORS file.

I had missed an umlaut, and misused a capital letter.

Author: robinwatts

CONTRIBUTORS

@@ -5,7 +5,7 @@ these contributions, and while privacy/brevity/confidentiality
 prevent us from listing everyone here, we would like to thank
 the following in particular:
 
- * Simon Bunzli (Zeniko, of the SumatraPDF project).
+ * Simon B�nzli (zeniko, of the SumatraPDF project).
 
  * Krzysztof Kowalczyk (of the SumatraPDF project).