Improve model card with metadata and description

This PR improves the model card by:

- Adding the `pipeline_tag: text-classification` to indicate its use in text classification preprocessing.
- Specifying the `library_name: fasttext` as it's a fastText-based filter.
- Confirming the `license: mit`.
- Providing a more descriptive model card.

This makes the model and its purpose clearer to users.

README.md

@@ -1,6 +1,25 @@
 ---
 license: mit
+pipeline_tag: text-classification
+library_name: fasttext
 ---
-This is the fastText pretraining data filter targeting
-the PIQA task, discussed in the main text of the Perplexity
-Correlations paper: https://arxiv.org/abs/2409.05816
+
+This is the fastText pretraining data filter targeting the PIQA task, discussed in the main text of the Perplexity Correlations paper: https://arxiv.org/abs/2409.05816.  This filter helps select high-quality pretraining data by identifying strong correlations between LLM perplexity on a given text and its downstream performance on a target benchmark (PIQA in this case). The filter is trained using perplexity correlations from a sample of 90 LLMs from the Open LLM Leaderboard on texts from tens of thousands of web domains.
+
+The filter is implemented using the `fasttext` library and can be used to select or weight pretraining data samples based on their predicted likelihood of improving downstream performance.
+
+For more information on the methodology and usage, please refer to the [Perplexity Correlations paper](https://arxiv.org/abs/2409.05816) and the [project repository](https://github.com/TristanThrush/perplexity-correlations).
+
+```python
+import fasttext
+
+# Load the pre-trained fastText model
+model = fasttext.load_model('fasttext_filter.bin')
+
+# Example usage: Get the 'include' probability for a piece of text
+text = "Some text to filter."
+prediction = model.predict(text)[0] # Prediction is 'include' or 'exclude'
+probability = model.predict_proba(text)[0][0] if prediction[0] == '__label__include' else model.predict_proba(text)[0][1] # probability of 'include'
+
+print(f"Prediction: {prediction[0]}, Probability: {probability}")
+```