Add IFEval score to metrics

This adds the prompt-level-loose accuracy metric from Google's IFEval benchmark: https://arxiv.org/abs/2311.07911

README.md

@@ -14,6 +14,23 @@ tags:
 - convAI
 - conversational
 pipeline_tag: text-generation
+model-index:
+- name: phi-2-super
+  results:
+  # IFEval
+  - task: 
+      type: text-generation
+      name: Text Generation
+    dataset:
+      name: Instruction Following Eval
+      type: wis-k/instruction-following-eval
+    metrics:
+       - type: acc
+         name: prompt_level_loose_acc
+         value: 0.2717
+    source:
+      name: LightEval
+      url: https://github.com/huggingface/lighteval
 ---
 # Phi-2-super (SFT + cDPO)