option to pay annually! (Patreon)

hello! i've added the option to pledge annually if you'd prefer to consolidate your pledges into once per year instead of paying once every month. 

this page explains more about the option: https://support.patreon.com/hc/en-us/articles/360042152671-I-paid-a-creator-for-a-year-what-can-I-expect-