docs: Add note for sigterm event

platform-includes/configuration/drain-example/javascript.node.mdx

@@ -2,6 +2,8 @@ The `close` method optionally takes a timeout in milliseconds and returns a
 promise that resolves when all pending events are flushed, or the timeout kicks
 in.
 
+Note that you can call this method on `SIGTERM` to gracefully shut down a service or container.
+
 ```javascript
 Sentry.close(2000).then(function () {
  process.exit();