docs(readme): add known issues section to readme and fill with keycha… (#648)

…in auth

Signed-off-by: Tomasz Grzegorzek <tgrzegorzek@nvidia.com>

Author: prokotg

README.md

@@ -157,3 +157,8 @@ This project is licensed under the Apache License 2.0. See the [LICENSE](https:/
 - **Issues**: [GitHub Issues](https://github.com/NVIDIA-NeMo/Evaluator/issues)
 - **Discussions**: [GitHub Discussions](https://github.com/NVIDIA-NeMo/Evaluator/discussions)
 - **Documentation**: [NeMo Evaluator Documentation](https://docs.nvidia.com/nemo/evaluator/latest/)
+
+
+## 🐛 Known issues
+
+- `nel ls` might require docker authenthication and currently does not support fetching credentials from known password management systems such as MacOS's Keychain or GNOME Keyring.