docs: Prepare for new sub tree

See #11925

docs/content/en/functions/go-template/len.md

@@ -1,51 +0,0 @@
----
-title: len
-description: Returns the length of a string, slice, map, or collection.
-categories: []
-keywords: []
-action:
-  aliases: []
-  related:
-    - functions/strings/Count
-    - functions/strings/CountRunes
-    - functions/strings/CountWords
-    - functions/strings/RuneCount
-  returnType: int
-  signatures: [len VALUE]
-aliases: [/functions/len]
----
-
-With a string:
-
-```go-html-template
-{{ "ab" | len }} → 2
-{{ "" | len }} → 0
-```
-
-With a slice:
-
-```go-html-template
-{{ slice "a" "b" | len }} → 2
-{{ slice | len }} → 0
-```
-
-With a map:
-
-```go-html-template
-{{ dict "a" 1 "b" 2  | len }} → 2
-{{ dict | len }} → 0
-```
-
-With a collection:
-
-```go-html-template
-{{ site.RegularPages | len }} → 42
-```
-
-You may also determine the number of pages in a collection with:
-
-```go-html-template
-{{ site.RegularPages.Len }} → 42
-```
-
-{{% include "functions/go-template/_common/text-template.md" %}}