add dco-check as action

Signed-off-by: FABIAN FAULHABER <fabian.faulhaber@mercedes-benz.com>

.github/workflows/dco-check.yml

@@ -0,0 +1,24 @@
+name: DCO Check
+
+on: [pull_request]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check for DCO
+        id: dco-check
+        uses: tisonkun/actions-dco@v1.1
+      - name: Comment about DCO status
+        uses: actions/github-script@v6
+        if: ${{ failure() }}
+        with:
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `Thank your for your contribution! Please make sure to agree to our DCO by including a  \
+              a Signed-off-by message in your commits. You can find the DCO as in our [contributing guide](https://github.com/mercedes-benz/disclosure-cli/blob/main/CONTRIBUTING.md). \
+              One or more of your commits is missing this message.`
+            })