Added basic example with includes

examples/application/src/main.rs

@@ -0,0 +1,15 @@
+extern crate actix_web;
+use actix_web::{App, Responder, HttpRequest, http::Method};
+
+// <setup>
+fn index(req: HttpRequest) -> impl Responder {
+    "Hello world!"
+}
+
+fn main() {
+    let app = App::new()
+        .prefix("/app")
+        .resource("/index.html", |r| r.method(Method::GET).f(index))
+        .finish();
+}
+// </setup>