fix bug in building page

.gitlab-ci.yml

@@ -3,9 +3,10 @@ image: alpine:latest
 pages:
   stage: deploy
   script:
-  - echo 'Nothing to do...'
+  - echo 'Move _build/html to public...'
+  - mv _build/html public
   artifacts:
     paths:
-    - _build/html
+    - public
   only:
   - master