upmerge commit signoff (#1299)

Signed-off-by: Brooke Hamilton <[email protected]>

.github/workflows/upmerge.yaml

@@ -68,7 +68,7 @@ jobs:
           git fetch origin $SOURCE_BRANCH
           git merge --no-commit origin/$SOURCE_BRANCH
           git checkout edge -- docs/config.toml docs/layouts/partials/hooks/body-end.html
-          git commit -m "Upmerge to edge"
+          git commit --signoff --message "Upmerge to edge"
           
           if git diff --quiet edge; then
               echo "No changes to merge from $SOURCE_BRANCH to edge"