Merge branch 'documentation' into 'master'

Insert install step

See merge request !28

.gitlab-ci.yml

@@ -16,6 +16,9 @@ build-documentation:
   stage: build_documentation
   script:
     - yarn docs:build
+    - npm install --force --global yarn
+    - yarn install
+    - yarn docs:build
   artifacts:
     paths:
       - styleguide