Updated Drupal to 8.6. This goes with the following updates because it's possible...

[yaffs-website] / web / core / modules / field_layout / field_layout.info.yml

name: 'Field Layout'
type: module
description: 'Adds layout capabilities to the Field UI.'
package: Core (Experimental)
version: VERSION
core: 8.x
dependencies:
  - drupal:layout_discovery