Add missing attribution.

Author: schlatterbeck

CHANGES.txt

@@ -84,7 +84,8 @@ Fixed:
 - Fix another XSS with the "otk" parameter, thanks to Jesse Ruderman for
   reporting. (Ralf)
 - Mark cookies HttpOnly and -- if https is used -- secure. Fixes
-  issue2550689, but is untested if this really works in browsers. (Ralf)
+  issue2550689, but is untested if this really works in browsers.
+  Thanks to Joseph Myers for reporting. (Ralf)
 
 
 2011-07-15: 1.4.19