Update README.md with license information

Hi, I'm Chen, a DevRel specialist from 01.AI.
We have updated our license from yi-license to apache-2.0, and this PR is about the update for your model.
Apache-2.0 enables more free and flexible use and distribution, promoting open collaboration and innovation.
If it looks good to you, you can update other Yi model derivatives now licensed under yi-license to apache-2.0.
Thanks for your understanding and cooperation.

README.md

@@ -1,10 +1,8 @@
 ---
-license: other
-license_link: https://huggingface.co/01-ai/Yi-6B/blob/main/LICENSE  
-license_name: yi-license
-model_creator: 01-ai  
-model_name:  Yi 6B  
-model_type:  yi
+model_creator: 01-ai
+model_name: Yi 6B
+model_type: yi
+license: apache-2.0
 ---
 
 # Model Card for Model ID