Fix build

Author: brokenfloppydisk

.github/workflows/build_docs.yml

@@ -28,7 +28,7 @@ jobs:
         run: |
           git fetch origin
           git checkout -b gh-pages origin/gh-pages
-          cp ../_build ./
+          cp -r ../_build ./
           git config --global user.name "CAMS SDD"
           git config --global user.email "${GITHUB_ACTOR}@users.noreply.github.com"
           git add ./.