DOC: Fix typo in TradingAlgorithm doc string.
DOC: Fix typo in TradingAlgorithm doc string.

sketchytechky/zipline,alphaBenj/zipline,michaeljohnbennett/zipline,wilsonkichoi/zipline,aajtodd/zipline,florentchandelier/zipline,erikness/AlephOne,wubr2000/zipline,keir-rex/zipline,cmorgan/zipline,kmather73/zipline,florentchandelier/zipline,zhoulingjun/zipline,kmather73/zipline,sketchytechky/zipline,dkushner/zipline,MonoCloud/zipline,StratsOn/zipline,quantopian/zipline,aajtodd/zipline,chrjxj/zipline,enigmampc/catalyst,gwulfs/zipline,ChinaQuants/zipline,stkubr/zipline,michaeljohnbennett/zipline,dkushner/zipline,CDSFinance/zipline,grundgruen/zipline,bartosh/zipline,jimgoo/zipline-fork,magne-max/zipline-ja,otmaneJai/Zipline,joequant/zipline,DVegaCapital/zipline,nborggren/zipline,humdings/zipline,morrisonwudi/zipline,semio/zipline,stkubr/zipline,ronalcc/zipline,YuepengGuo/zipline,YuepengGuo/zipline,Scapogo/zipline,grundgruen/zipline,ChinaQuants/zipline,umuzungu/zipline,dmitriz/zipline,humdings/zipline,iamkingmaker/zipline,wubr2000/zipline,enigmampc/catalyst,euri10/zipline,jordancheah/zipline,joequant/zipline,AlirezaShahabi/zipline,MonoCloud/zipline,zhoulingjun/zipline,euri10/zipline,otmaneJai/Zipline,StratsOn/zipline,semio/zipline,gwulfs/zipline,alphaBenj/zipline,cmorgan/zipline,wilsonkichoi/zipline,umuzungu/zipline,keir-rex/zipline,ronalcc/zipline,magne-max/zipline-ja,Scapogo/zipline,CDSFinance/zipline,nborggren/zipline,chrjxj/zipline,quantopian/zipline,erikness/AlephOne,jimgoo/zipline-fork,DVegaCapital/zipline,jordancheah/zipline,bartosh/zipline,AlirezaShahabi/zipline,iamkingmaker/zipline,morrisonwudi/zipline,dmitriz/zipline