CI Config: Publish built docs again

Using a copy of the docs artifacts for packing up
should not exhibit the problems from earlier.

.gitlab-ci.yml

@@ -9,6 +9,11 @@ docs:
   stage: "build"
   script:
     - "nix-shell --run 'nix-build docs.nix'"
+    - "cp --recursive --no-preserve=mode result/docs/.* docs/build/"
+  artifacts:
+    paths:
+      - "docs/build/"
+    expose_as: "docs-${CI_COMMIT_SHORT_SHA}"
 
 unit-tests:
   stage: "test"