[GH ARC]: Docs for setup of ARC, yaml manifests, config and gpu based cloudrunner code.

[jaiakash]

What you would like to be added?

Add documentation for setting up GitHub Actions Runner Controller (ARC) with GPU support in the cncfkubeflow tenancy.

• ARC installation steps and controller setup.
• Example YAML manifests for deploying ARC with GPU-enabled runners.
• Configuration details for secrets, tokens, and resource limits.
• How to integrate with GPU-based cloudrunner code (custom bootstrap, Terraform, OCI setup).

Related Issue: #2809 This setups self runner, Current issue is for setup of ARC

CNCF CPU Runners: https://github.com/cncf/automation/tree/main/ci/cloudrunners

Why is this needed?

• Provides a single reference point for ARC + GPU setup in the project.
• [Planned] Add GPU based runner to upstream https://github.com/cncf/automation

Love this feature?

Give it a 👍 We prioritize the features with most 👍

[jaiakash]

/assign @jaiakash
/area llm
/area gsoc

[andreyvelich]

/remove-label lifecycle/needs-triage
/area testing