Update README.md - typo

Author: mjsML

README.md

@@ -27,7 +27,7 @@ As of September 2022, this code is now in maintenance mode.
 The notebooks needed to make all the figures are available at the following locations.
 
 * [All notebooks (sorted by filename)](https://probml.github.io/notebooks)
-* [Book 1 notebooks (sorted by chaper)](https://github.com/probml/pyprobml/tree/master/notebooks/book1)
+* [Book 1 notebooks (sorted by chapter)](https://github.com/probml/pyprobml/tree/master/notebooks/book1)
 * [Book 2 notebooks (sorted by chapter)](https://github.com/probml/pyprobml/tree/master/notebooks/book2).