Add .gitlab-ci.yml

.gitlab-ci.yml

+# This file is a template, and might need editing before it works on your project.
+# Full project: https://gitlab.com/pages/plain-html
+image: python:3.6
+
+pages:
+  stage: deploy
+  script:
+    - python3 -m pip install mkdocs mkdocs-material mkdocstrings
+    - mkdocs build
+  artifacts:
+    paths:
+      - site
+  only:
+    - master