add explicit language tags to dev-guide code blocks
add explicit language tags to dev-guide code blocks

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