Grammar: Fix "it's" vs "its" in several places (#2518)

examples/low-level-rustls/src/main.rs

@@ -68,7 +68,7 @@ async fn main() {
             // `TokioIo` converts between them.
             let stream = TokioIo::new(stream);
 
-            // Hyper has also its own `Service` trait and doesn't use tower. We can use
+            // Hyper also has its own `Service` trait and doesn't use tower. We can use
             // `hyper::service::service_fn` to create a hyper `Service` that calls our app through
             // `tower::Service::call`.
             let hyper_service = hyper::service::service_fn(move |request: Request<Incoming>| {