MC-40328: cms_page_view_selectable layout update issue with multistore and multitheme (#8589)

* MC-40328: cms_page_view_selectable layout update issue with multistore and multitheme

* Update src/guides/v2.3/frontend-dev-guide/layouts/xml-manage.md

Co-authored-by: Jeff Matthews <matthews.jeffery@gmail.com>

Co-authored-by: Roman Flowers <flowers@adobe.com>
Co-authored-by: Jeff Matthews <matthews.jeffery@gmail.com>

Author: 3 people

src/guides/v2.3/frontend-dev-guide/layouts/product-layouts.md

@@ -65,4 +65,4 @@ Layout file | Description
 `wishlist_index_configure_type_grouped.xml` | Layout from this file is applied to `grouped` product only
 `wishlist_index_configure_type_simple.xml` | Layout from this file is applied to `simple` product only
 
-For setting a custom layout on specific category, product, and CMS pages, see [Common layout customization tasks]({{ page.baseurl }}/frontend-dev-guide/layouts/xml-manage.html#create-cms-pageproductcategory-specific-layouts).
+For setting a custom layout on specific category, product, and CMS pages, see [Common layout customization tasks]({{ page.baseurl }}/frontend-dev-guide/layouts/xml-manage.html#create-cms-pageproductcategory-specific-selectable-layouts).

src/guides/v2.3/frontend-dev-guide/layouts/xml-manage.md

@@ -689,11 +689,15 @@ You can remove navigation links from the 'My Account' dashboard on the storefron
 <referenceBlock name="customer-account-navigation-return-history-link" remove="true"/>
 ```
 
-## Create cms-page/product/category-specific layouts
+## Create cms-page/product/category-specific selectable layouts
 
 As of Magento 2.3.4, merchants can select layout updates to be applied to specific Category/Product/CMS Page pages on the frontend. These layout
 updates are made by creating layout XML files following specific naming conventions.
 
+{:.bs-callout-info}
+Selectable layout updates can only be loaded from the global store theme and work only in the single website with single theme configurations.
+If a specific entity like `cms-page/product/category` has an individual theme applied in the design configuration tab, the selected theme will have priority over the selected layout update.
+
 For Categories:
 
 -  `catalog_category_view_selectable_<Category ID>_<Layout Update Name>.xml`