ci(doc): build doc on gitlab pages

.gitlab-ci.yml

@@ -5,6 +5,7 @@ stages:
   - tests
   - after-tests
   - qa
+  - deploy
 
 lint_py:
   except:
@@ -45,7 +46,10 @@ lint_doc:
     - pip install tox
   script:
     - tox -e doc
-  allow_failure: true  # XXX fix me
+  artifacts:
+    paths:
+      - .tox/doc/tmp/html
+  allow_failure: true # XXX fix me
 
 py3_server:
   except:
@@ -164,3 +168,16 @@ sonarqube:
       --define sonar.projectName=${CI_PROJECT_TITLE}
       --define sonar.links.homepage=${CI_PROJECT_URL}
       --define sonar.host.url=${SONAR_URL}
+
+pages:
+  stage: deploy
+  before_script:
+    - pip install tox
+  script:
+    - tox -e doc
+    - mv .tox/doc/tmp/html public
+  artifacts:
+    paths:
+      - public
+  only:
+    - branch/default