doc: documented default statusCode

PR-URL: #28982
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/api/http.md

@@ -1402,7 +1402,7 @@ const server = http.createServer((req, res) => {
 added: v0.4.0
 -->
 
-* {number}
+* {number} **Default:** `200`
 
 When using implicit headers (not calling [`response.writeHead()`][] explicitly),
 this property controls the status code that will be sent to the client when