Fix simple typo

Resolves #1524

Author: hollasch

books/RayTracingTheRestOfYourLife.html

@@ -1388,7 +1388,7 @@
 this vector produced points that lay exactly on the unit sphere and thereby represent a random
 direction. This process of generating samples and rejecting them if they are not inside a desired
 space is called _the rejection method_, and is found all over the literature. The method covered
-last chapter is referred to as _the inversion method_ because we invert a PDF.
+in the last chapter is referred to as _the inversion method_ because we invert a PDF.
 
 Every direction in 3D space has an associated point on the unit sphere and can be generated by
 solving for the vector that travels from the origin to that associated point. You can think of