Add information to model card

This PR adds information to the model card by linking it to the paper [LANTERN: Accelerating Visual Autoregressive Models with Relaxed Speculative Decoding](https://huggingface.co/papers/2410.03355).

It also adds a pipeline tag, ensuring it can be found at https://huggingface.co/models?pipeline_tag=text-to-image, and adds `library_name: transformers`.

README.md

@@ -1,3 +1,9 @@
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-license: apache-2.0
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+---
+license: apache-2.0
+library_name: transformers
+pipeline_tag: text-to-image
+---
+
+This repository contains the model described in [LANTERN: Accelerating Visual Autoregressive Models with Relaxed Speculative Decoding](https://huggingface.co/papers/2410.03355).
+
+Code: https://github.com/jadohu/LANTERN