docs: Prepare for new sub tree

See #11925

docs/content/en/functions/strings/SliceString.md

@@ -1,20 +0,0 @@
----
-title: strings.SliceString
-description: Creates a slice of a half-open range, including start and end indices.
-categories: []
-keywords: []
-action:
-  aliases: [slicestr]
-  related: []
-  returnType: string
-  signatures: ['strings.SliceString STRING START [END]']
-aliases: [/functions/slicestr]
----
-
-For example, 1 and 4 creates a slice including elements 1 through 3.
-The `end` index can be omitted; it defaults to the string's length.
-
-```go-html-template
-{{ slicestr "BatMan" 3 }}` → Man
-{{ slicestr "BatMan" 0 3 }}` → Bat
-```