[ci] Check out repository before building docs

Author: dmitry-kabanov

.github/workflows/docs.yaml

@@ -15,6 +15,8 @@ jobs:
     build-docs:
         runs-on: ubuntu-22.04
         steps:
+            - name: Check out repository code
+              uses: actions/checkout@v4
             - name: install-doc-deps
               run: |
                   sudo apt install -y doxygen &&