docs: fix collect yaml branch

Author: kkkky123

.github/workflows/daily-stats.yml

@@ -15,10 +15,10 @@ jobs:
       contents: write
 
     steps:
-      - name: Checkout master branch
+      - name: Checkout main branch
         uses: actions/checkout@v4
         with:
-          ref: master
+          ref: main
 
       - name: Fetch current stats.json from gh-pages
         run: |