Update README.md (facebookresearch#1693)

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README.md

@@ -49,7 +49,7 @@ Habitat-Lab uses [`Habitat-Sim`](https://github.com/facebookresearch/habitat-sim
 
 
 ## Citing Habitat
-If you use the Habitat platform in your research, please cite the [Habitat 1.0](https://arxiv.org/abs/1904.01201)[Habitat 2.0](https://arxiv.org/abs/2106.14405), and [Habitat 3.0](https://arxiv.org/abs/2310.13724) papers:
+If you use the Habitat platform in your research, please cite the [Habitat 1.0](https://arxiv.org/abs/1904.01201), [Habitat 2.0](https://arxiv.org/abs/2106.14405), and [Habitat 3.0](https://arxiv.org/abs/2310.13724) papers:
 
 ```
 @misc{puig2023habitat3,