add more badges to README from shields.io
add more badges to README from shields.io

mwest1066/PrairieLearn,tbretl/PrairieLearn,mwest1066/PrairieLearn,rbessick5/PrairieLearn,parasgithub/PrairieLearn,tbretl/PrairieLearn,rbessick5/PrairieLearn,tbretl/PrairieLearn,rbessick5/PrairieLearn,mwest1066/PrairieLearn,jakebailey/PrairieLearn,parasgithub/PrairieLearn,mwest1066/PrairieLearn,jakebailey/PrairieLearn,parasgithub/PrairieLearn,tbretl/PrairieLearn,parasgithub/PrairieLearn,rbessick5/PrairieLearn,parasgithub/PrairieLearn,tbretl/PrairieLearn,jakebailey/PrairieLearn,mwest1066/PrairieLearn,rbessick5/PrairieLearn,jakebailey/PrairieLearn