doc: hello addon example should return "world"

The N-API version of the hello example, returned "hello" instead of
"world".

PR-URL: https://github.com/nodejs/node/pull/26328
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

doc/api/addons.md

@@ -408,7 +408,7 @@ napi_value Method(napi_env env, napi_callback_info args) {
   napi_value greeting;
   napi_status status;
 
-  status = napi_create_string_utf8(env, "hello", NAPI_AUTO_LENGTH, &greeting);
+  status = napi_create_string_utf8(env, "world", NAPI_AUTO_LENGTH, &greeting);
   if (status != napi_ok) return nullptr;
   return greeting;
 }