add empty encodings download

Author: Carlos Gomes

text_to_image/README.md

@@ -116,6 +116,7 @@ To download this data, run the following:
 cd /dataset
 bash <(curl -s https://raw.githubusercontent.com/mlcommons/r2-downloader/refs/heads/main/mlc-r2-downloader.sh) https://training.mlcommons-storage.org/metadata/flux-1-cc12m-preprocessed.uri
 bash <(curl -s https://raw.githubusercontent.com/mlcommons/r2-downloader/refs/heads/main/mlc-r2-downloader.sh) https://training.mlcommons-storage.org/metadata/flux-1-coco-preprocessed.uri
+bash <(curl -s https://raw.githubusercontent.com/mlcommons/r2-downloader/refs/heads/main/mlc-r2-downloader.sh) https://training.mlcommons-storage.org/metadata/flux-1-empty-encodings.uri
 ```
 
 The above requires ~2.5TB of storage.