add merge tag

To make it easier to identify merge models, we're experimenting with adding a `merge` tag for models created via a merge.

README.md

@@ -85,6 +85,8 @@ model-index:
     - type: acc
       value: 67.78
       name: accuracy
+tags:
+- merge
 ---
 ![image/png](https://cdn-uploads.huggingface.co/production/uploads/6468ce47e134d050a58aa89c/x44nNbPTpv0zGTqA1Jb2q.png)
 
@@ -167,4 +169,4 @@ Detailed results can be found [here](https://huggingface.co/datasets/open-llm-le
 | MMLU (5-shot)         | 64.26         |
 | TruthfulQA (0-shot)   | 62.78  |
 | Winogrande (5-shot)   | 79.16  |
-| GSM8K (5-shot)        | 67.78        |
+| GSM8K (5-shot)        | 67.78        |