docs(container): fix registry endpoint in example (#1375)

Author: Codelax

docs/resources/container.md

@@ -26,7 +26,7 @@ resource scaleway_container main {
     name = "my-container-02"
     description = "environment variables test"
     namespace_id = scaleway_container_namespace.main.id
-    registry_image = "${scaleway_container_namespace.main.endpoint}/alpine:test"
+    registry_image = "${scaleway_container_namespace.main.registry_endpoint}/alpine:test"
     port = 9997
     cpu_limit = 140
     memory_limit = 256