docs: Prepare for new sub tree

See #11925

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

@@ -1,37 +0,0 @@
----
-title: collections.First
-description: Returns the given collection, limited to the first N elements.
-categories: []
-keywords: []
-action:
-  aliases: [first]
-  related:
-    - functions/collections/After
-    - functions/collections/Last
-    - methods/pages/Limit
-  returnType: any
-  signatures: [collections.First N COLLECTION]
-aliases: [/functions/first]
----
-
-```go-html-template
-{{ range first 5 .Pages }}
-  {{ .Render "summary" }}
-{{ end }}
-```
-
-Set `N` to zero to return an empty collection.
-
-```go-html-template
-{{ $emptyPageCollection := first 0 .Pages}}
-```
-
-Use `first` and [`where`] together.
-
-```go-html-template
-{{ range where .Pages "Section" "articles" | first 5 }}
-  {{ .Render "summary" }}
-{{ end }}
-```
-
-[`where`]: /functions/collections/where