docs: add empty line before commit comment body

Author: szkiba

.github/workflows/extension-registry-changed.yml

@@ -27,7 +27,8 @@ jobs:
       - name: Update
         run: |
           if ! git diff -s --exit-code registry.json; then
-            echo "Automatic update\n" > build/msg.txt
+            echo "Automatic update" > build/msg.txt
+            echo "" >> build/msg.txt
             ${{ github.workspace }}/.github/compare build/registry.json registry.json >> build/msg.txt
             git config --local user.email 'wayback[bot]@users.noreply.github.com'
             git config --local user.name 'wayback[bot]'