document the background behavior
document the background behavior

Ref: https://github.com/sindresorhus/anatine/commit/0f6ded55ae1089c345f37bbed9a039c7919a9f59

vinnyang/caprine,antonio-ramadas/caprine,vinnyang/caprine,chabou/caprine,sindresorhus/caprine,sindresorhus/caprine,veniversum/caprine