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

@@ -1,14 +1,11 @@
 ---
 language:
 - en
-license: other
 datasets:
 - ehartford/dolphin
 - jondurbin/airoboros-2.2.1
 - ehartford/samantha-data
 - ehartford/WizardLM_evol_instruct_V2_196k_unfiltered_merged_split
-license_name: yi-license
-license_link: LICENSE
 model-index:
 - name: dolphin-2.2-yi-34b-200k
   results:
@@ -112,6 +109,7 @@ model-index:
     source:
       url: https://huggingface.co/spaces/HuggingFaceH4/open_llm_leaderboard?query=ehartford/dolphin-2.2-yi-34b-200k
       name: Open LLM Leaderboard
+license: apache-2.0
 ---
 
 Dolphin 2.2 🐬