fix a small code example in the readme
fix a small code example in the readme

cortex/sqlx,jmoiron/sqlx,aiyi/sqlx,johnsto/sqlx,beni55/sqlx,larsth/sqlx,wmydz1/sqlx,adcaes/sqlx,outrightmental/go-sqlx,proteneer/sqlx,snikch/sqlx,StabbyCutyou/sqlx