Fix misspelling of "missspelling". =) Thanks to Jesus Climent.

debian/changelog

@@ -25,7 +25,7 @@ dpkg (1.13.17) unstable; urgency=low
   [ Guillem Jover ]
   * Add missing parentheses surrounding a man page section reference
     in the dpkg-source man page (Matt Kraai). Closes: #353731
-  * Fix missspelling of "occurred" as "occoured" in dpkg-gencontrol and
+  * Fix misspelling of "occurred" as "occoured" in dpkg-gencontrol and
     dpkg-source (Matt Kraai). Closes: #353949
   * Major cleanup of manpages, by using properly the bold and italic
     attributes and other embellishments.