docs: Prepare for new sub tree

See #11925

docs/content/en/functions/collections/Group.md

@@ -1,31 +0,0 @@
----
-title: collections.Group
-description: Groups the given page collection by the given key.
-categories: []
-keywords: []
-action:
-  aliases: [group]
-  related: []
-  returnType: any
-  signatures: [collections.Group KEY PAGES]
-aliases: [/functions/group]
----
-
-```go-html-template
-{{ $new := .Site.RegularPages | first 10 | group "New" }}
-{{ $old := .Site.RegularPages | last 10 | group "Old" }}
-{{ $groups := slice $new $old }}
-{{ range $groups }}
-  <h3>{{ .Key }}{{/* Prints "New", "Old" */}}</h3>
-  <ul>
-    {{ range .Pages }}
-      <li>
-        <a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a>
-        <div class="meta">{{ .Date.Format "Mon, Jan 2, 2006" }}</div>
-      </li>
-    {{ end }}
-  </ul>
-{{ end }}
-```
-
-The page group you get from `group` is of the same type you get from the built-in [group methods](/templates/lists#group-content) in Hugo. The above example can be [paginated](/templates/pagination/#list-paginator-pages).