gitlab-ci: Fix pages generation for the documentation

Fixes 0a13641ff: "gitlab-ci: Enable gitlab page for publishing documentation",
to point to correct sphinx documentation.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>

.gitlab-ci.yml

@@ -71,7 +71,7 @@ pages:
   script:
   - export PREFIX=$(pwd)/prefix-weston-build-native-meson
   - mkdir public
-  - cp -R $PREFIX/share/weston-doc/* public/
+  - cp -R $PREFIX/share/doc/weston/* public/
   artifacts:
     paths:
     - public