doc: document http2 network error behaviour

Fixes: nodejs#21836

PR-URL: nodejs#21861
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Minwoo Jung <[email protected]>

Author: addaleax

doc/api/http2.md

@@ -272,12 +272,17 @@ server.on('stream', (stream, headers) => {
     'content-type': 'text/html',
     ':status': 200
   });
+  stream.on('error', (error) => console.error(error));
   stream.end('<h1>Hello World</h1>');
 });
 
 server.listen(80);
 ```
 
+Even though HTTP/2 streams and network sockets are not in a 1:1 correspondence,
+a network error will destroy each individual stream and must be handled on the
+stream level, as shown above.
+
 #### Event: 'timeout'
 <!-- YAML
 added: v8.4.0