Russ Poldrack’s open-source book “Statistical Thinking for the 21st century” Link replacement required

[given](http://statsthinking21.org/fitting-models-to-data.html) is broken. 

> The new link is [https://statsthinking21.github.io/statsthinking21-core-site/fitting-models.html](https://statsthinking21.github.io/statsthinking21-core-site/fitting-models.html)