docs(readme): update links to demo and docs
docs(readme): update links to demo and docs

Signed-off-by: Will Soto <e88b744add47cc3da30186f5601865928acd804d@gmail.com>

willsoto/ng-chartist,willsoto/ng-chartist,paradox41/angular2-chartist,willsoto/angular2-chartist,willsoto/angular2-chartist,willsoto/ng-chartist,paradox41/angular2-chartist,paradox41/angular2-chartist,willsoto/angular2-chartist