docs: Prepare for new sub tree

See #11925

docs/content/en/methods/menu-entry/Parent.md

@@ -1,50 +0,0 @@
----
-title: Parent
-description: Returns the `parent` property of the given menu entry.
-categories: []
-keywords: []
-action:
-  related: []
-  returnType: string
-  signatures: [MENUENTRY.Parent]
----
-
-With this menu definition:
-
-{{< code-toggle file=hugo >}}
-[[menus.main]]
-name = 'Products'
-pageRef = '/product'
-weight = 10
-
-[[menus.main]]
-name = 'Product 1'
-pageRef = '/products/product-1'
-parent = 'Products'
-weight = 1
-
-[[menus.main]]
-name = 'Product 2'
-pageRef = '/products/product-2'
-parent = 'Products'
-weight = 2
-{{< /code-toggle >}}
-
-This template renders the nested menu, listing the `parent` property next each of the child entries:
-
-```go-html-template
-<ul>
-  {{ range .Site.Menus.main }}
-    <li>
-      <a href="{{ .URL }}">{{ .Name }}</a>
-      {{ if .HasChildren }}
-        <ul>
-          {{ range .Children }}
-            <li><a href="{{ .URL }}">{{ .Name }}</a> ({{ .Parent  }})</li>
-          {{ end }}
-        </ul>
-      {{ end }}
-    </li>
-  {{ end }}
-</ul>
-```