the example should be simpler (#760)

Author: lemire

README.md

@@ -73,7 +73,7 @@ Linux or macOS users might follow the following instructions if they have a rece
     #include <iostream>
 
     int main(int, char *[]) {
-      auto url = ada::parse<ada::url>("https://www.google.com");
+      auto url = ada::parse("https://www.google.com");
       if (!url) {
         std::cout << "failure" << std::endl;
         return EXIT_FAILURE;