fix(docs): Updated llamastack pod metadata (#4983)

# What does this PR do?
<!-- Provide a short summary of what this PR does and why. Link to
relevant issues if applicable. -->

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->

## Test Plan
<!-- Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.* -->

<!-- For API changes, include:
1. A testing script (Python, curl, etc.) that exercises the new/modified
endpoints
2. The output from running your script

Example:
```python
...
...
```

Output:
```
<paste actual output here>
```
-->

Author: gyliu513

docs/docs/deploying/kubernetes_deployment.mdx

@@ -201,10 +201,10 @@ Wait for the Llama Stack server pod to be ready:
 kubectl get llamastackdistribution llamastack-vllm
 
 # Check the pods created by the operator
-kubectl get pods -l app.kubernetes.io/name=llama-stack
+kubectl get pods -l app.kubernetes.io/instance=llamastack-vllm
 
 # Wait for the pod to be ready
-kubectl wait --for=condition=ready pod -l app.kubernetes.io/name=llama-stack --timeout=300s
+kubectl wait --for=condition=ready pod -l app.kubernetes.io/instance=llamastack-vllm --timeout=300s
 ```
 
 Get the service name created by the operator (it typically follows the pattern `<llamastackdistribution-name>-service`):