chore(docs): update node.md

The import name needs to be corrected. I'm just changing the name to the correct one.

docs/src/guide/node.md

@@ -289,7 +289,7 @@ the type otherwise.
 <script setup>
 import { markRaw } from 'vue'
 import CustomNode from './CustomNode.vue'
-import CustomNode from './OverwriteCustomNode.vue'
+import OverwriteCustomNode from './OverwriteCustomNode.vue'
 import SpecialNode from './SpecialNode.vue'
 
 const nodeTypes = {