feat: add instructions for setting a dashboard password and create secret.yaml template

kubernetes/manifests/secret.yaml

@@ -0,0 +1,15 @@
+# Source: krawl-chart/templates/secret.yaml
+# Uncomment and set your dashboard password below.
+# If not created, the password will be auto-generated and printed in the pod logs.
+#
+# apiVersion: v1
+# kind: Secret
+# metadata:
+#   name: krawl-dashboard
+#   namespace: krawl-system
+#   labels:
+#     app.kubernetes.io/name: krawl
+#     app.kubernetes.io/instance: krawl
+# type: Opaque
+# stringData:
+#   dashboard-password: "your-secret-password"