Add .gitlab-ci.yml

.gitlab-ci.yml

+trigger_docs_generation:
+  stage: build
+  only:
+    changes:
+      - validata_core/schemas.toml
+  script: 
+    - "curl -X POST -F token=$TOKEN -F ref=master https://git.opendatafrance.net/api/v4/projects/13/trigger/pipeline"
\ No newline at end of file