Provide more details for opaque examples in guide.

Closes #1100.

site/guide/4-requests.md

@@ -735,20 +735,15 @@ use rocket::request::FlashMessage;
 
 #[get("/")]
 fn bad(cookies: Cookies, flash: FlashMessage) {
+    // Oh no! `flash` holds a reference to `Cookies` too!
     let msg = flash.msg();
 }
-```
-
-```rust
-# #[macro_use] extern crate rocket;
-# fn main() {}
-
-# use rocket::http::Cookies;
-# use rocket::request::FlashMessage;
 
 #[get("/")]
 fn good(cookies: Cookies, flash: FlashMessage) {
     std::mem::drop(cookies);
+
+    // Now, `flash` holds an _exclusive_ reference to `Cookies`. Whew.
     let msg = flash.msg();
 }
 ```

site/guide/6-state.md

@@ -331,6 +331,13 @@ fn get_logs(conn: LogsDbConn, id: usize) -> Logs {
 }
 ```
 
+! note The above examples uses [Diesel] with some fictional `Logs` type.
+
+  The example above contains the use of a `Logs` type that is application
+  specific and not built into Rocket. It also uses [Diesel]'s query-building
+  syntax. Rocket does not provide an ORM. It is up to you to decide how to model
+  your application's data.
+
 If your application uses features of a database engine that are not available
 by default, for example support for `chrono` or `uuid`, you may enable those
 features by adding them in `Cargo.toml` like so:

site/guide/8-testing.md

@@ -205,7 +205,7 @@ We do this by checking the `Response` object directly:
 
 # use rocket::local::Client;
 use rocket::http::{ContentType, Status};
-
+#
 # let rocket = rocket::ignite().mount("/", routes![hello]);
 # let client = Client::new(rocket).expect("valid rocket instance");
 # let mut response = client.get("/").dispatch();