Add example of constructor without new for String() (mdn#19864)

* Add example of constructor without new

* Less trivial examples

Author: teoli2003

files/en-us/web/javascript/reference/global_objects/string/index.md

@@ -113,10 +113,14 @@ will automatically wrap the string primitive and call the method or perform the
 lookup on the wrapper object instead.
 
 ```js
-const strPrim = 'foo';
-const strObj = new String(strPrim);
+const strPrim = "foo"; // A literal is a string primitive
+const strPrim2 = String(1); // Coerced into the string primitive "1"
+const strPrim3 = String(true); // Coerced into the string primitive "true"
+const strObj = new String(strPrim); // String with new returns a string wrapper object.
 
 console.log(typeof strPrim); // Logs "string"
+console.log(typeof strPrim2); // Logs "string"
+console.log(typeof strPrim3); // Logs "string"
 console.log(typeof strObj);  // Logs "object"
 ```