Replace Disk Usage TUI with Disktree (#14426)

manual/21-tuis.md

@@ -26,10 +26,6 @@ You start it (or reattach to your existing session) with `Super + Ctrl + Return`
 
 Omarchy has packaged this as _About_ in the Omarchy menu (`Super + Space`).
 
-## Disk Usage
-
-When the drive fills up and you have no idea what's eating it, launch _Disk Usage_ from the app launcher (`Super + Space`). It's [dua](https://github.com/Byron/dua-cli) in interactive mode pointed at the whole file system, so you can walk down into whatever directory is the culprit, sorted biggest first, and delete from right inside it.
-
 ## Cliamp
 
 [Cliamp](https://www.cliamp.stream/) is a retro terminal music player inspired by Winamp 2.x, complete with built-in radio stations for lo-fi beats. Launch it with `Super + Shift + Alt + M`, or from the Omarchy menu under _Apps_. Press `?` for the full keybinding list.

manual/22-guis.md

@@ -8,6 +8,10 @@ Plug in a USB stick or an SD card and it's mounted automatically, so it just sho
 
 Double-clicking follows sensible defaults: images open in imv, video in mpv, PDFs in Document Viewer, and plain text in Neovim.
 
+## Disktree
+
+When the drive fills up and you have no idea what's eating it, launch [Disktree](https://github.com/tobi/disktree) from the app launcher (`Super + Space`). It shows a graphical treemap of your home directory. Larger blocks take up more space; walk into directories with the keyboard or mouse, mark what should go, and review your selections before removing anything. Run `disktree --disk` to scan the whole disk.
+
 ## Obsidian
 
 [Obsidian](https://obsidian.md/) is a free and highly extensible note taking application that uses simple Markdown files for storage.