Removed duplicate line

Author: trevordblack

books/RayTracingInOneWeekend.html

@@ -1856,7 +1856,6 @@
     color ray_color(const ray& r, const hittable& world, int depth) {
         hit_record rec;
 
-
         // If we've exceeded the ray bounce limit, no more light is gathered.
         if (depth <= 0)
             return color(0,0,0);