fix create_course.sh link (#197)
fix create_course.sh link (#197)

Update create course link from  - https://github.com/Submitty/Submitty/blob/master/bin/create_course.sh > to 
https://github.com/Submitty/Submitty/blob/master/sbin/create_course.sh
Submitty/submitty.github.io,Submitty/submitty.github.io,Submitty/submitty.github.io,Submitty/submitty.github.io