Reference RHEL tutorial validation tests in README

[nv-rinig]

Updates the RHEL tutorial's README to show users how to run the newly added validation tests.

[greptile-apps]

Confidence Score: 5/5

[Low risk] Adds tutorial validation test references to build documentation.

The PR appears safe to merge; no actionable issue was established.

Summary

Adds instructions to run the RHEL tutorial's CPU and GPU checks as server QA tests.

• Shows how to mount the server checkout's qa/ directory into the tutorial images.
• Adds QA model generation and a command for running the PyTorch backend tests.
• No actionable issues were established. The linked server QA scripts were not available for inspection, so their requirements remain unverified.

_{Reviews (1) · Last reviewed commit: "Reference RHEL tutorial validation tests..." · Reviewed by Greptile}