Apply suggestions from code review

Author: archibate

docs/type_rich_api.md

@@ -1587,11 +1587,11 @@ public:
 struct Name : Typed<Name, std::string> {};
 
 struct Meter : Typed<Meter, double> {
-    Meter(double value) : Typed<Meter, double>(value) {};
+    using Typed<Kilometer, double>::Typed;
 };
 
 struct Kilometer : Typed<Kilometer, double> {
-    Kilometer(double value) : Typed<Kilometer, double>(value) {};
+    using Typed<Kilometer, double>::Typed;
     operator Meter() const {
         // 允许隐式转换为米
         return Meter(value * 1000);