Fix typo in next week chapter two

Resolves #504

Author: hollasch

books/RayTracingTheNextWeek.html

@@ -41,12 +41,12 @@
 Motion Blur
 ====================================================================================================
 
-When you decided to ray trace, you decided visual quality was worth more run-time. In your fuzzy
-reflection and defocus blur you needed multiple samples per pixel. Once you have taken a step down
-that road, the good news is that almost all effects can be brute-forced. Motion blur is certainly
-one of those. In a real camera, the shutter opens and stays open for a time interval, and the camera
-and objects may move during that time. Its really an average of what the camera sees over that
-interval that we want.
+When you decided to ray trace, you decided that visual quality was worth more than run-time. In your
+fuzzy reflection and defocus blur you needed multiple samples per pixel. Once you have taken a step
+down that road, the good news is that almost all effects can be brute-forced. Motion blur is
+certainly one of those. In a real camera, the shutter opens and stays open for a time interval, and
+the camera and objects may move during that time. Its really an average of what the camera sees over
+that interval that we want.
 
 
 Introduction of SpaceTime Ray Tracing