Fix markdown issue

$ markdownlint '**/*.md' --config .gitlab/ci/config/markdownlint.yml -p .gitlab/ci/config/markdownlintignore.txt
FAQ_articles/services-adullact/demarches-simplifiees/utilisation-de-API-GraphQL/_index.md:171 MD046/code-block-style Code block style [Expected: indented; Actual: fenced]

assigned to @mfaure

created branch 228-fix-markdown-issue to address this issue

mentioned in commit 3f397a5a

mentioned in commit 7e36a886