Add Git commit message for terraform-docs

* Creates a commit message the same as the Renovate commit message, with
  '- Terraform Docs' appended

.github/workflows/continuous-integration-terraform.yml

@@ -77,6 +77,10 @@ jobs:
         run: |
           echo "$GITHUB_PR_BRANCH"
 
+      - name: Output Git commit message (Debugging)
+        run: |
+          echo "${{ github.event.commits[0].message }}"
+
       - name: Generate Terraform docs
         uses: terraform-docs/[email protected]
         if: "!startsWith(env.GITHUB_PR_BRANCH, 'renovate/')"
@@ -97,3 +101,4 @@ jobs:
           output-method: inject
           git-push: true
           ref: ${{ github.event.pull_request.head.ref }}
+          git-commit-message: ${{ github.event.commits[0].message }} - Terraform Docs