Update changelog to include SGLang/vLLM related updates (#516)

## What does this PR do?

**Type of change:** doc update

**Overview:** update changelog

## Usage
<!-- You can potentially add a usage example below. -->

```python
# Add a code snippet demonstrating how to use this
```

## Testing
<!-- Mention how have you tested your change if applicable. -->

## Before your PR is "*Ready for review*"
<!-- If you haven't finished some of the above items you can still open
`Draft` PR. -->

- **Make sure you read and follow [Contributor
guidelines](https://github.com/NVIDIA/TensorRT-Model-Optimizer/blob/main/CONTRIBUTING.md)**
and your commits are signed.
- **Is this change backward compatible?**: Yes/No <!--- If No, explain
why. -->
- **Did you write any new necessary tests?**: Yes/No
- **Did you add or update any necessary documentation?**: Yes/No
- **Did you update
[Changelog](https://github.com/NVIDIA/TensorRT-Model-Optimizer/blob/main/CHANGELOG.rst)?**:
Yes/No <!--- Only for new features, API changes, critical bug fixes or
bw breaking changes. -->

## Additional Information
<!-- E.g. related issue. -->

Signed-off-by: Zhiyu Cheng <[email protected]>

Author: Edwardf0t1

CHANGELOG.rst

@@ -31,6 +31,8 @@ Model Optimizer Changelog (Linux)
 - Add support for Nemotron Nano VL v1 & v2 models in FP8/NVFP4 PTQ workflow.
 - Add flags ``nodes_to_include`` and ``op_types_to_include`` in AutoCast to force-include nodes in low precision, even if they would otherwise be excluded by other rules.
 - Add support for ``torch.compile`` and benchmarking in ``examples/diffusers/quantization/diffusion_trt.py``.
+- Enabled native Modelopt quantization support for FP8 and NVFP4 formats in SGLang. See `SGLang quantization documentation <https://github.com/sgl-project/sglang/blob/main/docs/advanced_features/quantization.md#using-nvidia-modelopt>`_ for more details.
+- Added modelopt quantized checkpoints in vLLM/SGLang CI/CD pipelines (PRs are under review).
 
 **Documentation**