DOC: Add missing word in docstring.
DOC: Add missing word in docstring.

humdings/zipline,alphaBenj/zipline,magne-max/zipline-ja,umuzungu/zipline,florentchandelier/zipline,bartosh/zipline,Scapogo/zipline,umuzungu/zipline,quantopian/zipline,florentchandelier/zipline,bartosh/zipline,wilsonkichoi/zipline,humdings/zipline,magne-max/zipline-ja,quantopian/zipline,Scapogo/zipline,enigmampc/catalyst,wilsonkichoi/zipline,alphaBenj/zipline,enigmampc/catalyst