Add functional support matrix to README

[snowmanwwg]

Added a broad functional support matrix to the README.

What does this PR do ?

Add a one line overview of what this PR aims to accomplish.

Changelog

• Add specific line by line info of high level changes in this PR.

GitHub Actions CI

See the CI section in the Contributing doc for how to trigger the CI. A Nvidia developer will need to approve and trigger the CI for external contributors.

Before your PR is "Ready for review"

Pre checks:

• Make sure you read and followed Contributor guidelines
• Did you write any new necessary tests?
• Did you add or update any necessary documentation?
• Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  • Reviewer: Does the PR have correct import guards for all optional libraries?

If you haven't finished some of the above items you can still open "Draft" PR.

Additional Information

• Related to # (issue)

[claude]

Light Code Review

Docs-only change — small and straightforward. One typo flagged inline:

• Typo: "SFT Lora" in the table header should be "SFT LoRA" (capital A) to match "RL LoRA" in the same row and the standard acronym.

Everything else looks good.

Suggested test cases

No perf tests impacted.

[yaoyu-33]

/ok to test a04fb76