Add evaluation results on xsum dataset

Beep boop, I am a bot from Hugging Face's automatic model evaluator 👋!\
Your model has been evaluated on the [xsum](https://huggingface.co/datasets/xsum) dataset by

@sheikmohdimran

, using the predictions stored [here](https://huggingface.co/datasets/autoevaluate/autoeval-staging-eval-project-xsum-3c39b441-10285368).\
Accept this pull request to see the results displayed on the [Hub leaderboard](https://huggingface.co/spaces/autoevaluate/leaderboards?dataset=xsum).\
Evaluate your model on more datasets [here](https://huggingface.co/spaces/autoevaluate/model-evaluator?dataset=xsum).

README.md

@@ -2,6 +2,42 @@
 language: en
 tags:
 - summarization
+model-index:
+- name: google/pegasus-xsum
+  results:
+  - task:
+      type: summarization
+      name: Summarization
+    dataset:
+      name: xsum
+      type: xsum
+      config: default
+      split: test
+    metrics:
+    - name: ROUGE-1
+      type: rouge
+      value: 46.8623
+      verified: true
+    - name: ROUGE-2
+      type: rouge
+      value: 24.4533
+      verified: true
+    - name: ROUGE-L
+      type: rouge
+      value: 39.0548
+      verified: true
+    - name: ROUGE-LSUM
+      type: rouge
+      value: 39.0994
+      verified: true
+    - name: loss
+      type: loss
+      value: 1.5717021226882935
+      verified: true
+    - name: gen_len
+      type: gen_len
+      value: 22.8821
+      verified: true
 ---
 
 ### Pegasus Models