home page: show "course instances" vs "courses" depending on our access level; close #526
home page: show "course instances" vs "courses" depending on our access level; close #526

lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack,mwest1066/PrairieLearn,kevinwang/PrairieLearn,kevinwang/PrairieLearn,parasgithub/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,PrairieLearn/PrairieLearnHack,rbessick5/PrairieLearn,lotrfan/PrairieLearn,tbretl/PrairieLearn,rbessick5/PrairieLearn,kevinwang/PrairieLearn,kevinwang/PrairieLearn,jakebailey/PrairieLearn,lotrfan/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,PrairieLearn/PrairieLearnHack,lotrfan/PrairieLearn,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,tbretl/PrairieLearn,jakebailey/PrairieLearn,rbessick5/PrairieLearn,mwest1066/PrairieLearn,lotrfan/PrairieLearn,kevinwang/PrairieLearn,lotrfan/PrairieLearn,tbretl/PrairieLearn,kevinwang/PrairieLearn,kevinwang/PrairieLearn,parasgithub/PrairieLearn,rbessick5/PrairieLearn,mwest1066/PrairieLearn,parasgithub/PrairieLearn,rbessick5/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,PrairieLearn/PrairieLearnHack,PrairieLearn/PrairieLearnHack,lotrfan/PrairieLearn,mwest1066/PrairieLearn,parasgithub/PrairieLearn