ci: consistent spelling in auto-generation workflows

Author: chrisgrieser

.github/workflows/panvimdoc.yml

@@ -25,5 +25,5 @@ jobs:
           description: " Auto-generated from README.md. Do not make PRs to this file."
       - uses: stefanzweifel/git-auto-commit-action@v4
         with:
-          commit_message: "chore: Auto-generate vimdocs"
+          commit_message: "chore: auto-generate vimdocs"
           branch: ${{ github.head_ref }}