r/containers-image: Fix registries.conf path

`/etc/containers/registries.conf.d` is distinct from
`/etc/containers/registries.d`.  The latter contains YAML files relating
to image signatures, while the former contains TOML files relating to
registry locations.

roles/containers-image/tasks/main.yml

@@ -1,7 +1,7 @@
 - name: ensure container registries are configured
   template:
     src: registries.conf.j2
-    dest: /etc/containers/registries.d/40-registries.conf
+    dest: /etc/containers/registries.conf.d/40-registries.conf
     owner: root
     group: root
     mode: u=rw,go=r