Readme updates

[EiffL]

This pull request updates the README.md to improve clarity, highlight available resources, and provide more comprehensive acknowledgments. The most important changes are grouped below:

Documentation and Resource Updates:

• Added a Hugging Face model badge and link to the header, making it easier for users to access the model directly.
• Updated the navigation links to include a "Tutorials" section, helping users find learning resources more easily.
• Removed the "Alpha Testing" section, simplifying instructions and assuming general availability of model weights.
• Added a new "Model" column to the model variants table, with a direct link to the base model and placeholders for upcoming models.
• Removed a redundant reference to the online documentation, streamlining the quick start section.

Acknowledgments:

• Expanded the acknowledgments section to recognize support from the Simons Foundation, Schmidt Sciences, GENCI at IDRIS, and the Flatiron Institute, providing transparency about project resources and support.