Fixed link in README.md
Fixed link in README.md

The GitHub link could be https://github.com/gpu
(without "s"), but the website should be OK, too

dividiti/CLBlast,gpu/CLBlast,gpu/CLBlast,CNugteren/CLBlast,CNugteren/CLBlast,gpu/CLBlast,dividiti/CLBlast,CNugteren/CLBlast,dividiti/CLBlast