Add model card

This PR adds a model card and links the model to the paper page and code repository. It also adds a pipeline tag, ensuring people can find it at
https://huggingface.co/models?pipeline_tag=unconditional-image-generation

README.md

@@ -1,3 +1,8 @@
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-license: mit
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+---
+license: mit
+pipeline_tag: unconditional-image-generation
+---
+
+This model is introduced in the paper [Reconstruction vs. Generation: Taming Optimization Dilemma in Latent Diffusion Models](https://arxiv.org/abs/2501.01423).
+
+Code: https://github.com/hustvl/mar.