add hint comment for user

Author: lhw362950217

start.bash

@@ -11,6 +11,14 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+
+cat <<EOF
+This script is safe to re-run, feel free to retry when it exits abnormally.
+Especially when we are waiting for a pod in Kubernetes cluster, it may
+pull image from registry and take a lot of time to startup.
+
+EOF
+
 if [[ "$(whoami)" != "root" ]]; then
     echo "Please change to root user and retry."
     exit 1