Update README.md

Author: hailwood

README.md

@@ -29,6 +29,8 @@ Several of these helpers are disabled by default but can be enabled in the confi
  - Adds a new "Meta Title" field
  - Automatically applied
 
+If you do not add the `HasOnAfterUpdateCMSFieldsExtensionPoint` trait to your base `Page` class then the extension will use an unreliable method of moving the pages. For this reason we suggest adding `use HasOnAfterUpdateCMSFieldsExtensionPoint;` to this class. 
+ 
 ##FooterMenuExtension##
  - Adds a new *ShowInFooter* option to the page settings
  - Adds a new `FooterPages()` function to the SiteTree to return only pages that have this checked
@@ -54,4 +56,4 @@ Several of these helpers are disabled by default but can be enabled in the confi
 ##OwnerPermissionedDataObject##
  - Allows data objects to inherit the access permissions from their attached relation parent
  - Relation parent defaults to `Page()`
- - If `static::$relationOwner` is set to `null` will fall back to asking the standard `Page` for permission
+ - If `static::$relationOwner` is set to `null` will fall back to asking the standard `Page` for permission