Drop Amazon links

Author: Steve Hollasch

books/README-InOneWeekend.md

@@ -50,7 +50,6 @@ review the [CONTRIBUTING][] document for the most effective way to proceed.
 
 
 
-[Amazon.com]:               https://amazon.com/dp/B01B5AODD8
 [CONTRIBUTING]:             ../CONTRIBUTING.md
 [releases]:                 https://github.com/raytracing/raytracing.github.io/releases/
 [Hack the Hood]:            https://hackthehood.org/

books/README-TheNextWeek.md

@@ -48,7 +48,6 @@ Jean Buckley for editing.
 
 
 
-[Amazon.com]:                 https://amazon.com/dp/B01CO7PQ8C
 [CONTRIBUTING]:               ../CONTRIBUTING.md
 [directly from GitHub]:       https://github.com/raytracing/raytracing.github.io/releases/
 [Hack the Hood]:              http://www.hackthehood.org

books/README-TheRestOfYourLife.md

@@ -54,7 +54,6 @@ book to Markdeep and moving it to the web.
 
 
 
-[Amazon.com]:                 https://amazon.com/dp/B01DN58P8C
 [CONTRIBUTING]:               ../CONTRIBUTING.md
 [directly from GitHub]:       https://github.com/raytracing/raytracing.github.io/releases/
 [Hack the Hood]:              http://www.hackthehood.org/