Update README.md

README.md

@@ -191,6 +191,11 @@ We refer the reader to the [SantaCoder model page](https://huggingface.co/bigcod
 - **Point of Contact:** [contact@bigcode-project.org](mailto:contact@bigcode-project.org)
 - **Languages:** Python, Java, and JavaScript
 
+There are two versions (branches) of the model:
+* `main`: Uses the `gpt_bigcode` model. [Requires the bigcode fork of transformers](https://github.com/bigcode-project/transformers).
+* `main_custom`: Packaged with its modeling code. Requires `transformers>=4.27`.
+  Alternatively, it can run on older versions by setting the configuration parameter `activation_function = "gelu_pytorch_tanh"`.
+
 # Use
 
 ## Intended use