docs: Prepare for new sub tree

See #11925

docs/content/en/functions/os/ReadDir.md

@@ -1,51 +0,0 @@
----
-title: os.ReadDir
-description: Returns an array of FileInfo structures sorted by file name, one element for each directory entry.
-categories: []
-keywords: []
-action:
-  aliases: [readDir]
-  related:
-    - functions/os/FileExists
-    - functions/os/Getenv
-    - functions/os/ReadFile
-    - functions/os/Stat
-  returnType: os.FileInfo
-  signatures: [os.ReadDir PATH]
-aliases: [/functions/readdir]
----
-
-The `os.ReadDir` function resolves the path relative to the root of your project directory. A leading path separator (`/`) is optional.
-
-With this directory structure:
-
-```text
-content/
-├── about.md
-├── contact.md
-└── news/
-    ├── article-1.md
-    └── article-2.md
-```
-
-This template code:
-
-```go-html-template
-{{ range readDir "content" }}
-  {{ .Name }} → {{ .IsDir }}
-{{ end }}
-```
-
-Produces:
-
-```html
-about.md → false
-contact.md → false
-news → true
-```
-
-Note that `os.ReadDir` is not recursive.
-
-Details of the `FileInfo` structure are available in the [Go documentation](https://pkg.go.dev/io/fs#FileInfo).
-
-For more information on using `readDir` and `readFile` in your templates, see [Local File Templates](/templates/files).