Fix: Rename v1beta1 example directory to v1

The SDK bump graduated the dashboard resource from v1beta1 to v1,
but the example directory was not renamed. This caused TestAccExamples
to fail looking for examples/resources/grafana_apps_dashboard_dashboard_v1/.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: dprokop

docs/resources/apps_dashboard_dashboard_v1.md

@@ -14,7 +14,25 @@ Manages Grafana dashboards using the new Grafana APIs.
 * [Official documentation](https://grafana.com/docs/grafana/latest/dashboards/)
 * [HTTP API](https://grafana.com/docs/grafana/latest/developers/http_api/dashboard/#new-dashboard-apis)
 
-
+## Example Usage
+
+```terraform
+resource "grafana_apps_dashboard_dashboard_v1beta1" "example" {
+  metadata {
+    uid = "example-dashboard"
+  }
+
+  spec {
+    title = "Example Dashboard"
+    json = jsonencode({
+      title         = "Example Dashboard"
+      uid           = "example-dashboard"
+      panels        = []
+      schemaVersion = 42
+    })
+  }
+}
+```
 
 <!-- schema generated by tfplugindocs -->
 ## Schema