Issue #2193577 by benjy: Rename Block Layout to Block layout for consistency.

core/modules/block/block.local_tasks.yml

@@ -5,11 +5,11 @@ block.admin_edit:
 
 # Per theme block layout pages.
 block.admin_display:
-  title: 'Block Layout'
+  title: 'Block layout'
   route_name: block.admin_display
   base_route: block.admin_display
 block.admin_display_theme:
-  title: 'Block Layout'
+  title: 'Block layout'
   route_name: block.admin_display_theme
   parent_id: block.admin_display
   derivative: 'Drupal\block\Plugin\Derivative\ThemeLocalTask'