Update doc.yml

Author: Eleirbag89

.github/workflows/doc.yml

@@ -9,6 +9,8 @@ jobs:
   deploy:
     runs-on: ubuntu-20.04
     steps:
+      - name: Checkout source
+        uses: actions/checkout@v1
       - name: Generate docs
         uses: mattnotmitt/[email protected]
         with: