Add highlight to new hittable::bounding_box()

Resolves #442

Author: hollasch

CHANGELOG.md

@@ -7,6 +7,7 @@ Change Log -- Ray Tracing in One Weekend
 ### _The Next Week_
 - Fix: `shared_ptr` dereference and simplify code in `hittable_list::bounding_box()` (#435)
 - Fix: erroneous en-dash in code block (#439)
+- Fix: Add highlight to new `hittable::bounding_box()` method (#442)
 
 
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books/RayTracingTheNextWeek.html

@@ -615,7 +615,9 @@
         public:
             virtual bool hit(
                 const ray& r, double t_min, double t_max, hit_record& rec) const = 0;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++ highlight
             virtual bool bounding_box(double t0, double t1, aabb& output_box) const = 0;
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
     };
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [hittable-bbox]: <kbd>[hittable.h]</kbd> Hittable class with bounding-box]