doc: fix napi_open_callback_scope description

DaAitch · addaleax · commit f8bb544bfbd1 · 2019-01-14T16:50:54.000+01:00
- parameter `resource_object` is mandatory PR-URL: #25366 Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
diff --git a/doc/api/n-api.md b/doc/api/n-api.md
@@ -4118,7 +4118,7 @@ NAPI_EXTERN napi_status napi_open_callback_scope(napi_env env,
                                                  napi_callback_scope* result)
 ```
 - `[in] env`: The environment that the API is invoked under.
-- `[in] resource_object`: An optional object associated with the async work
+- `[in] resource_object`: An object associated with the async work
   that will be passed to possible `async_hooks` [`init` hooks][].
 - `[in] context`: Context for the async operation that is
 invoking the callback. This should be a value previously obtained
