add helper converters into response

guide/src/qs_2.md

@@ -64,8 +64,8 @@ extern crate actix;
 extern crate actix_web;
 use actix_web::prelude::*;
 
-fn index(req: HttpRequest) -> Result<HttpResponse> {
-    Ok(httpcodes::HTTPOk.with_body("Hello world!"))
+fn index(req: HttpRequest) -> &'static str {
+    "Hello world!"
 }
 
 fn main() {

guide/src/qs_3.md

@@ -47,11 +47,11 @@ struct AppState {
     counter: Cell<usize>,
 }
 
-fn index(req: HttpRequest<AppState>) -> HttpResponse {
+fn index(req: HttpRequest<AppState>) -> String {
     let count = req.state().counter.get() + 1; // <- get count
     req.state().counter.set(count);            // <- store new count in state
-    httpcodes::HTTPOk.with_body(               // <- response with count
-        format!("Num of requests: {}", count))
+
+    format!("Request number: {}", count)      // <- response with count
 }
 
 fn main() {