doc: add call-once note to napi_queue_async_work

Add note to `napi_queue_async_work()` indicating that, upon successful
return, it must not be called again with the same work item.

Fixes: https://github.com/nodejs/node/issues/27217
PR-URL: https://github.com/nodejs/node/pull/27582


Reviewed-By: Franziska Hinkelmann <franziska.hinkelmann@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>