Add RAG Blueprint to components.yml so sync workflow mirrors it

[kumar-punit]

The README already lists RAG Blueprint and links to skills/rag/, but the
component was never added to components.yml. The sync workflow only mirrors
components defined there, so skills/rag/ has never been populated and every
link to it 404s (flagged by Juana / Sumit in #skills).

• Add RAG Blueprint entry to components.yml
  (repo: NVIDIA-AI-Blueprints/rag, path: skill-source/.agents/skills/,
  catalog_dir: rag)
• Wrap the README's Version cell for RAG with the
  sync:rag-blueprint:version markers so the workflow can populate the SHA
  and date on the next run

After this lands, the next sync run will create skills/rag/ and update the
Version column automatically.

Onboarding type

• New product onboarding (components.yml entry)
• Other (catalog change, README fix, infrastructure, etc.)

For new product onboarding — author affirmations

By submitting this PR, I confirm on behalf of my team:

• Skills cleared for open source release per NVIDIA's internal IP review process (six-question check, all answers affirmative)
• License selected: Apache 2.0
• No new license or new third-party component introduced beyond what the source repo already carries
• Source repo is public and under an NVIDIA-owned GitHub org
• .agents/skills/ or skills/ path used for new entries (or existing path retained for legacy entries per components.yml)

NVIDIA contributors: see the internal onboarding guide for the IP review process details and license selection.

Reviewer checklist (OSS Skills PIC)

• Author confirmations above are checked
• components.yml entry valid (required fields, unique catalog_dir, path exists in source repo)
• SKILL.md frontmatter spec-compliant (at least one sampled)
• README rows added (Available Skills + Getting Help & Contributing)
• No new license or third-party dependency requiring OSRB filing

All PRs

• All commits signed off with DCO (git commit -s).
  If you forgot, run git rebase --signoff origin/main && git push --force-with-lease to retroactively sign all commits in your branch.

[mosheabr]

Approved. Clean fix for the RAG Blueprint orphan: components.yml entry valid, source path verified (skill-source/.agents/skills/rag-blueprint), Apache-2.0 license matches, IP-review affirmations complete, DCO signed off (first PR using the new template flow end-to-end — nicely done). Description in SKILL.md has rich trigger keywords addressing the distractor concern.

Merging now.