Add pages to .gitlab-ci.yml

This will be used for the tutorials

.gitlab-ci.yml

@@ -185,3 +185,17 @@ test-gnu-bin:
     - cd ../reparam
     - mpiexec -n 1 ../../../bin/sisso++
     - cd ../../../
+
+pages:
+  script:
+    - source cpp_sisso_env/bin/activate
+    - pip install mkdocs mkdocs-material pymdown-extensions mkdocs-minify-plugin
+    - mkdocs build
+    - mv site public
+  artifacts:
+    paths:
+    - public
+  only:
+  - master
+  - docs
+  - joss