doc: describe how to forbid the use of api-key param/header
fix gravitee-io/issues#2446
@@ -230,7 +230,8 @@ ds:
#tenant: europe
#policy:
-# Customize the api-key header and / or query parameter
+# Customize the api-key header and / or query parameter.
+# Set an empty value to prohibit its use.
# api-key:
# header: X-Gravitee-Api-Key
# param: api-key
