doc: update websocket link to avoid linking to self

The link `WebSocket` is pointing to the section itself.

PR-URL: #56897
Reviewed-By: Tim Perry <pimterry@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Matthew Aitken <maitken033380023@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>

doc/api/http.md

@@ -4256,7 +4256,7 @@ A browser-compatible implementation of [`WebSocket`][].
 [`Headers`]: globals.md#class-headers
 [`TypeError`]: errors.md#class-typeerror
 [`URL`]: url.md#the-whatwg-url-api
-[`WebSocket`]: #websocket
+[`WebSocket`]: https://developer.mozilla.org/en-US/docs/Web/API/WebSocket
 [`agent.createConnection()`]: #agentcreateconnectionoptions-callback
 [`agent.getName()`]: #agentgetnameoptions
 [`destroy()`]: #agentdestroy