L2SS-557: Add ci job to build sphinx documentation

.gitlab-ci.yml

@@ -9,6 +9,7 @@ stages:
   - images
   - building
   - linting
+  - documentation
   - static-analysis
   - unit-tests
   - integration-tests
@@ -322,6 +323,17 @@ shellcheck:
   script:
 #     TODO(Corne): Ignore shell files in submodules
     - shellcheck **/*.sh
+sphinx-documentation:
+  stage: documentation
+  before_script:
+    - sudo apt-get update
+    - sudo apt-get install -y git
+  script:
+    - cd tangostationcontrol
+    - tox -e docs
+  artifacts:
+    paths:
+      - tangostationcontrol/docs/build/
 unit_test:
   stage: unit-tests
   before_script: