Update README.rdoc
Update README.rdoc

Hopefully fixed Travis-CI build status
johnmarinelli/nmatrix,agisga/nmatrix,janusnic/nmatrix,johnmarinelli/nmatrix,janusnic/nmatrix,wlevine/nmatrix,thisMagpie/nmatrix,thisMagpie/nmatrix,johnmarinelli/nmatrix,agisga/nmatrix,wlevine/nmatrix,wlevine/nmatrix,thisMagpie/nmatrix,janusnic/nmatrix,agisga/nmatrix,wlevine/nmatrix,thisMagpie/nmatrix,johnmarinelli/nmatrix,janusnic/nmatrix,agisga/nmatrix