Add model card

This PR adds a model card for the LANTERN model, including the pipeline tag, license, library name, and links to the paper and code repository.

README.md

@@ -1,3 +1,9 @@
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-license: apache-2.0
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+---
+license: apache-2.0
+pipeline_tag: text-to-image
+library_name: transformers
+---
+
+This repository contains the official PyTorch implementation of the paper [LANTERN: Accelerating Visual Autoregressive Models via Relaxed Speculative Decoding](https://arxiv.org/abs/2410.03355).
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+Code: https://github.com/jadohu/LANTERN