fixed shift logic error in readme
fixed shift logic error in readme

shyamalschandra/asm.js,Uni-Sol/asm.js,dherman/asm.js,jeykigung/asm.js,jeykigung/asm.js,Uni-Sol/asm.js,gasman/asm.js,shyamalschandra/asm.js,gasman/asm.js,jeykigung/asm.js,dherman/asm.js,shyamalschandra/asm.js,Uni-Sol/asm.js,dherman/asm.js,gasman/asm.js