docs: add windows doc note in sample mkdir (#960)

## 📺 PR Description

Doc update for #959, Windows sample for config/cable directory,

## Checklist

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- [x] my commits **and PR title** follow the [conventional
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Author: clach04

docs/getting-started/03-first-channel.md

@@ -38,6 +38,7 @@ Let's build a channel to browse and preview TLDR pages (quick command references
 Create a new file:
 
 ```sh
+# NOTE for Microsoft Windows; md "%LOCALAPPDATA%\television\config\cable"
 mkdir -p ~/.config/television/cable
 touch ~/.config/television/cable/tldr.toml
 ```