derrickzhu/EllieSQL_Router_Checkpoints · Improve model card: Add pipeline tag, library name, GitHub link, and usage example

This PR enhances the model card for the EllieSQL router checkpoints.

Key improvements:

Adds pipeline_tag: text-classification for better discoverability, accurately reflecting the router model's function in classifying query complexity.
Adds library_name: transformers to indicate compatibility with the 🤗 Transformers library.
Integrates a direct link to the GitHub repository for easy access to the source code.
Includes a detailed Python code example demonstrating how to load and use one of the router models as a PEFT adapter for complexity classification.