Fix permissions configuration in README example (#285)

* Update README.md

Author: zimagen

README.md

@@ -60,12 +60,13 @@ on:
 jobs:
   automerge:
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: read
     steps:
       - id: automerge
         name: automerge
         uses: "pascalgn/automerge-action@v0.16.3"
-        permissions:
-          contents: write
         env:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
 ```