add doc on how to update changelog
add doc on how to update changelog

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