Update README.md to state the limitation of accessing GCS when conver… (#139)

Update README.md to state the limitation of accessing GCS when converting checkpoints.

Author: wang2yn84

README.md

@@ -84,6 +84,8 @@ huggingface-cli download mistralai/Mixtral-8x7B-v0.1 --local-dir $input_ckpt_dir
 
 ## Run weight safetensor convert
 
+There are limited support (only Llama models as of now) for accessing checkpoints on GCS. Accessing GCS takes a long time and therefore storing checkpoints to local is recommended.
+
 ```bash
 export input_ckpt_dir=Original llama weights directory
 export output_ckpt_dir=The output directory