Fix broken link to algorithm paper in readme

[Floyd]

The link the readme to https://www.aclweb.org/anthology/papers/D18-1384/d18-1384 ends in a 404. Assuming this is not just a problem on my end or a temporary problem with aclweb.org, we should update the link.

[Misha Balyasin]

Thanks for the report!
I've already found this issue and fixed in #45