Update Volcano integration doc

[annajung]

reviewers @tgaddair @kevin85421

Why are these changes needed?

• Update the Volcano integration doc to make it easier for users to follow the installation and example steps
• Move RayCluster yaml examples into /config/samples/
• Clarify that additional labels ray.io/priority-class-name and volcano.sh/queue-name requires the corresponding resources to be created first before creating a raycluster

Related issue number

Checks

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • This PR is not tested :(

[kevin85421]

@Darren221 is very new to both Kubernetes and KubeRay. He will conduct user testing on this document to determine whether it is clear enough for someone not very familiar with Kubernetes and KubeRay.

[Darren221]

I successfully reproduced the results using the provided documentation. While the instructions were clear and allowed me to achieve the expected outcomes, I found it challenging to fully grasp the benefits of Volcano integration from the document alone. Apart from this aspect, the material was quite beginner-friendly.

[kevin85421]

LGTM. Thank you for the contribution! This doc is pretty easy to follow. I just left a minor comment and I will merge it after it is addressed.

[kevin85421]

Suggested change

	# running: 2
	# running: 3

My output:

apiVersion: scheduling.volcano.sh/v1beta1
kind: PodGroup
metadata:
  creationTimestamp: "2023-09-06T04:54:03Z"
  generation: 5
  name: ray-test-cluster-1-pg
  namespace: default
  ownerReferences:
  - apiVersion: ray.io/v1alpha1
    blockOwnerDeletion: true
    controller: true
    kind: RayCluster
    name: test-cluster-1
    uid: 87967f54-a16b-4f58-b5d2-a9daf2a77f55
  resourceVersion: "3540"
  uid: 46338fd7-9463-481a-9d83-770727dc1b70
spec:
  minMember: 3
  minResources:
    cpu: "3"
    memory: 4Gi
  queue: kuberay-test-queue
status:
  conditions:
  - lastTransitionTime: "2023-09-06T04:54:04Z"
    message: '3/3 tasks in gang unschedulable: pod group is not ready, 3 Pending,
      3 minAvailable; Pending: 3 Unschedulable'
    reason: NotEnoughResources
    status: "True"
    transitionID: cb24f520-8156-4a62-ade9-1af71f74426c
    type: Unschedulable
  - lastTransitionTime: "2023-09-06T04:57:21Z"
    reason: tasks in gang are ready to be scheduled
    status: "True"
    transitionID: 990c7753-2c93-4c05-bc56-4b8b01c7f396
    type: Scheduled
  phase: Running
  running: 3

[annajung]

Thanks for catching that, updated

[kevin85421]

This PR only updates docs. The CI failures should be fixed after rebasing with the master branch. Merge.