improve python intro and scala web docs

Author: lihaoyi

docs/modules/ROOT/pages/pythonlib/intro.adoc

@@ -21,7 +21,8 @@ object `package` extends RootModule with ScalaModule {
   }
 }
 
-// This example demonstrates how to set up a simple Scala webserver
+// This example demonstrates how to set up a Scala webserver using the popular
+// https://http4s.org/[Http4S] web framework and associated libraries.
 // implementing the popular Todo-MVC demo application. It includes a test suite
 // that spins up the web server locally and makes HTTP requests against it.