update ai-toolchian-operator docs

[Fei-Guo]

This PR updates the product document to make clarifications about

1. the link to the latest supported model list.
2. the addon release is usually one release lag behind the upstream release (so that we don't have to update this doc every time we have a new addon release).
3. some old nvidia GPU skus are not supported.

[prmerger-automator]

@Fei-Guo : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[prmerger-automator]

@Fei-Guo : Thanks for your contribution! The author(s) and reviewer(s) have been notified to review your proposed change.

[learn-build-service-prod]

Learn Build status updates of commit a7fd1d1:

✅ Validation status: passed

File	Status	Preview URL	Details
articles/aks/ai-toolchain-operator-azure-portal.md	✅Succeeded
articles/aks/ai-toolchain-operator.md	✅Succeeded

For more details, please refer to the build report.

[v-regandowner]

@schaffererin

Can you review the proposed changes?

IMPORTANT: When the changes are ready for publication, adding a #sign-off comment is the best way to signal that the PR is ready for the review team to merge.

#label:"aq-pr-triaged"
@MicrosoftDocs/public-repo-pr-review-team