diff --git a/config/env.example.optional b/config/env.example.optional
index 9d9f1b003..f22c83893 100644
--- a/config/env.example.optional
+++ b/config/env.example.optional
@@ -39,6 +39,9 @@ DS_ENV="staging"
 # Instance customization: URL of the documentation website
 # DOC_URL="https://doc.demarches-simplifiees.fr"
 
+# Instance customization: URL of the Routage documentation
+# ROUTAGE_URL=""
+#
 # Instance customization: URL of the accessibility statement
 # ACCESSIBILITE_URL=""