chore(docs): update validation example

docs/examples/validation/CustomInput.vue

@@ -2,11 +2,15 @@
 import { Handle, Position } from '@vue-flow/core'
 
 const props = defineProps({
-  isValidTargetPos: {
-    type: Function,
-    required: false,
+  data: {
+    type: Object,
+    required: true,
   },
 })
+
+function isValidConnection(connection) {
+  return connection.target === props.data.validTarget && connection.source === props.data.validSource
+}
 </script>
 
 <script>
@@ -16,6 +20,6 @@ export default {
 </script>
 
 <template>
-  <div>Only connectable with B</div>
-  <Handle type="source" :position="Position.Right" :is-valid-connection="props.isValidTargetPos" />
+  <div>Only connectable with {{ data.validTarget }}</div>
+  <Handle type="source" :position="Position.Right" :is-valid-connection="isValidConnection" />
 </template>