docs/usage/accounts.rst: fix outdated example for getting & updating an account
docs/usage/accounts.rst: fix outdated example for getting & updating an account

Mobii/twilio-python,YeelerG/twilio-python,bcorwin/twilio-python,cinemapub/bright-response,RobSpectre/twilio-python,cinemapub/bright-response,clearcare/twilio-python,Stackdriver/twilio-python,supermanheng21/twilio-python,twilio/twilio-python,johannakate/twilio-python,Stackdriver/twilio-python,Rosy-S/twilio-python,tysonholub/twilio-python