Add model card

This PR adds a model card and links to the paper and code.

README.md

@@ -1,6 +1,13 @@
-This is the PosS-3 model of the paper **PosS:Position Specialist Generates Better Draft for Speculative Decoding**
+---
+library_name: transformers
+pipeline_tag: text-generation
+---
+
+This is the PosS-3 model of the paper [**PosS:Position Specialist Generates Better Draft for Speculative Decoding**](https://huggingface.co/papers/2506.03566).
+
+Code: https://github.com/shrango/PosS
 
 If the code fails to auto-download the models, you may mannually download the following files.
 
 - `pytorch_model.bin`: Model weights
-- `config.json`: Model config
+- `config.json`: Model config