docs: add Nemotron 3 Ultra NVFP4 blog to Latest News

[shljessie]

What does this PR do?

Adds a new entry to the Latest News section of README.md for the NVIDIA Developer blog post on quantizing Nemotron 3 Ultra (550B) to NVFP4 with Model Optimizer:

• Blog: Creating the NVIDIA Nemotron 3 Ultra NVFP4 Checkpoint with NVIDIA Model Optimizer
• Checkpoint: NVIDIA-Nemotron-3-Ultra-550B-A55B-NVFP4

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Summary by CodeRabbit

Summary by CodeRabbit

• Documentation
  • Updated the “Latest News” section with a new announcement for 2026/06/26 about the creation of the NVIDIA Nemotron 3 Ultra NVFP4 checkpoint using NVIDIA Model Optimizer.
  • Included throughput/accuracy highlights and a link to the related Hugging Face checkpoint.

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Reviewing files that changed from the base of the PR and between 26caf59 and b3bb2f8.

📒 Files selected for processing (1)

• README.md

🚧 Files skipped from review as they are similar to previous changes (1)

• README.md

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📝 Walkthrough

Walkthrough

README.md adds a 2026/06/26 “Latest News” entry announcing the NVIDIA Nemotron 3 Ultra NVFP4 checkpoint and linking to its blog post and Hugging Face checkpoint.

Changes

README Latest News Update

Layer / File(s)	Summary
Add checkpoint announcement README.md	Adds a dated entry describing the NVIDIA Nemotron 3 Ultra NVFP4 checkpoint, Model Optimizer usage, performance claims, and the related Hugging Face link.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Suggested reviewers: edwardf0t1

🚥 Pre-merge checks | ✅ 6

✅ Passed checks (6 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the documentation-only addition of the Nemotron 3 Ultra NVFP4 item to the Latest News section.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Security Anti-Patterns	✅ Passed	Only README.md changed; no modelopt/examples Python code, deps, or security-sensitive patterns were added.

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.89%. Comparing base (0593df0) to head (b3bb2f8).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

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+ Coverage   77.80%   77.89%   +0.09%     
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  Files         519      519              
  Lines       57960    59727    +1767     
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+ Hits        45095    46526    +1431     
- Misses      12865    13201     +336     

Flag	Coverage Δ
unit	55.46% <ø> (+0.22%)	⬆️

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[jenchen13]

Suggested change

- [2026/06/26] [BLOG: Creating the NVIDIA Nemotron 3 Ultra NVFP4 Checkpoint with NVIDIA Model Optimizer](https://developer.nvidia.com/blog/creating-the-nvidia-nemotron-3-ultra-nvfp4-checkpoint-with-nvidia-model-optimizer/): How we quantized Nemotron 3 Ultra (550B) to NVFP4 with Model Optimizer — up to 5.9× higher decode-heavy inference throughput than GLM-5.1 754B FP4 while matching BF16 accuracy. Checkpoint on Hugging Face: [NVFP4](https://huggingface.co/nvidia/NVIDIA-Nemotron-3-Ultra-550B-A55B-NVFP4).

- [2026/06/26] [BLOG: Creating the NVIDIA Nemotron 3 Ultra NVFP4 Checkpoint with NVIDIA Model Optimizer](https://developer.nvidia.com/blog/creating-the-nvidia-nemotron-3-ultra-nvfp4-checkpoint-with-nvidia-model-optimizer/): How we quantized Nemotron 3 Ultra (550B) to NVFP4 with Model Optimizer — up to 5.9× higher decode-heavy inference throughput than GLM-5.1 754B FP4 while matching BF16 accuracy. [NVFP4 Checkpoint](https://huggingface.co/nvidia/NVIDIA-Nemotron-3-Ultra-550B-A55B-NVFP4) on Hugging Face: .