fix: add quantity_point::origin, like std::chrono::time_point::clock

src/core/include/units/customization_points.h

@@ -88,7 +88,7 @@ struct quantity_like_traits;
 /**
  * @brief Provides support for external quantity point-like types
  * 
- * The type trait should provide the following nested type aliases: @c dimension, @c unit, @c rep,
+ * The type trait should provide the following nested type aliases: @c origin, @c unit, @c rep,
  * and a static member function @c relative(T) that will return the quantity-like value of the quantity point.
  * 
  * Usage example can be found in @c units/chrono.h header file.