clarified the grid example in the README
clarified the grid example in the README

davidwickman/assemble,a0000001/test,cgvarela/assemble,davidwickman/assemble,xetryj/assemble,edrohler/assemble,valentinvieriu/assemble,xetryj/assemble,avr/assemble,assemble/assemble,cgvarela/assemble,assemble/grunt-assemble,valentinvieriu/assemble,edrohler/assemble,assemble/grunt-assemble,assemble/assemble,makotot/assemble