Remove outdated credit

Modified-by: Travis Cross <tc@traviscross.com>
Signed-off-by: Travis Cross <tc@traviscross.com>

libs/libzrtp/AUTHORS

@@ -28,7 +28,5 @@ Thanks to:
 	Ariel Boston
 	Donovan Preston
 
-Software development services provided by Soft_industry http://www.soft-industry.com/en.
-
 Portions of this software are available under open source licenses from other authors.
 Notably, Brian Gladman's AES implementation, and David McGrew's libSRTP package.