Fix the broken link of Harry potter and the methods of rationality (#102)

The link to pdf was broken, the current link points to the site from which the user can decide if they want to read it online or download the PDF.

readme.md

@@ -413,7 +413,7 @@ _Please read [contribution guidelines](contributing.md) before contributing._
 - [📕 The road (2006)](https://www.goodreads.com/book/show/6288.The_Road)
 - [📖 The metamorphosis of prime intellect (2007)](http://localroger.com/prime-intellect/mopiidx.html)
 - [📕 The passage (2010)](https://www.goodreads.com/series/53226-the-passage)
-- [📖 Harry potter and the methods of rationality (2015)](http://www.hpmor.com/wordpress/wp-content/uploads/2012/03/Harry-Potter-and-the-Methods-of-Rationality.pdf)
+- [📖 Harry potter and the methods of rationality (2015)](https://hpmor.com/)
 - [📖 Unsong (2017)](http://unsongbook.com/)
 
 ### Adventure