Fix minor typo in csvpy docs.
Fix minor typo in csvpy docs.

tlevine/csvkit,Jobava/csvkit,archaeogeek/csvkit,unpingco/csvkit,kyeoh/csvkit,onyxfish/csvkit,wjr1985/csvkit,bradparks/csvkit__query_join_filter_CSV_cli,arowla/csvkit,KarrieK/csvkit,reubano/csvkit,bmispelon/csvkit,moradology/csvkit,elcritch/csvkit,snuggles08/csvkit,dannguyen/csvkit,gepuro/csvkit,wireservice/csvkit,Tabea-K/csvkit,jpalvarezf/csvkit,haginara/csvkit,matterker/csvkit,doganmeh/csvkit,metasoarous/csvkit,aequitas/csvkit,cypreess/csvkit,nriyer/csvkit,themiurgo/csvkit,barentsen/csvkit