docs(node): fix handler preset name and export

The Handler (advanced) section referenced preset `node` and export `listener`,
but `node` is an alias for `node-server` (not the middleware handler). The
actual preset name is `node-middleware` and the export is `middleware`.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: wadefletch

docs/2.deploy/10.runtimes/1.node.md

@@ -52,18 +52,18 @@ In addition to environment variables from the `node_server` preset, you can cust
 
 ## Handler (advanced)
 
-**Preset:** `node`
+**Preset:** `node_middleware`
 
-Nitro also has a more low-level preset that directly exports a function with `(req, res) => {}` signature usable for middleware and custom servers.
+Nitro also has a more low-level preset that directly exports a Node.js compatible handler usable for middleware and custom servers.
 
-When running `nitro build` with the Node preset, the result will be an entry point exporting a function with the `(req, res) => {}` signature.
+When running `nitro build` with the Node middleware preset, the result will be an entry point exporting a `middleware` handler.
 
 **Example:**
 
 ```js
 import { createServer } from 'node:http'
-import { listener } from './.output/server'
+import { middleware } from './.output/server'
 
-const server = createServer(listener)
+const server = createServer(middleware)
 server.listen(8080)
 ```