Broken link in readme.md

[justinpenner]

Here's an updated link to the Knuth and Plass article:
https://onlinelibrary.wiley.com/doi/abs/10.1002/spe.4380111102

[alerque]

This has already been reported and somebody has tried to fix it in #28. The contribution has not been accepted yet.

[justinpenner]

Ah, my mistake. I only looked in the Issues tab before posting.