updated doc

src/entt/entity/registry.hpp

@@ -450,9 +450,8 @@ public:
      * want to iterate entities and components in the expected order.
      *
      * @note
-     * Empty components aren't explicitly instantiated. Only one instance of the
-     * given type is created. Therefore, this function always returns a pointer
-     * to that instance.
+     * Empty components aren't explicitly instantiated. Therefore, this function
+     * isn't available for them. A compilation error will occur if invoked.
      *
      * @tparam Component Type of component in which one is interested.
      * @return A pointer to the array of components of the given type.