Fix a few typos in docs and comments (#2808)

examples/consume-body-in-extractor-or-middleware/src/main.rs

@@ -50,7 +50,7 @@ async fn print_request_body(request: Request, next: Next) -> Result<impl IntoRes
 async fn buffer_request_body(request: Request) -> Result<Request, Response> {
     let (parts, body) = request.into_parts();
 
-    // this wont work if the body is an long running stream
+    // this won't work if the body is an long running stream
     let bytes = body
         .collect()
         .await