Update README.md

README.md

@@ -64,6 +64,9 @@ The model was trained on [Japanese C4](https://huggingface.co/datasets/allenai/c
 # Tokenization
 The model uses a [sentencepiece](https://github.com/google/sentencepiece)-based tokenizer. The vocabulary was first trained on a selected subset from the training data using the official sentencepiece training script, and then augmented with emojis and symbols.
 
+# Release date
+January 26, 2022
+
 # How to cite
 ```bibtex
 @misc{rinna-japanese-gpt-1b,