fixed anchor link to http.IncomingMessage doc

Author: piepmatz

locale/en/docs/guides/anatomy-of-an-http-transaction.md

@@ -420,7 +420,7 @@ read through the API docs for [`EventEmitters`][], [`Streams`][], and [`HTTP`][]
 [`Server`]: https://nodejs.org/api/http.html#http_class_http_server
 [`listen`]: https://nodejs.org/api/http.html#http_server_listen_port_hostname_backlog_callback
 [API reference]: https://nodejs.org/api/http.html
-[`IncomingMessage`]: https://nodejs.org/api/http.html#http_http_incomingmessage
+[`IncomingMessage`]: https://nodejs.org/api/http.html#http_class_http_incomingmessage
 [`ReadableStream`]: https://nodejs.org/api/stream.html#stream_class_stream_readable
 [`rawHeaders`]: https://nodejs.org/api/http.html#http_message_rawheaders
 [`Buffer`]: https://nodejs.org/api/buffer.html