YAML files reference docs: windows_migration_enabled (#24891)

- Add missing reference docs for the following user story:
  - #22075

docs/Configuration/yaml-files.md

@@ -203,6 +203,7 @@ The `controls` section allows you to configure scripts and device management (MD
 
 - `scripts` is a list of paths to macOS, Windows, or Linux scripts.
 - `windows_enabled_and_configured` specifies whether or not to turn on Windows MDM features (default: `false`). Can only be configured for all teams (`default.yml`).
+- `windows_migration_enabled` specifies whether or not to automatically migrate Windows hosts connected to another MDM solution. If `false`, MDM is only turned on after hosts are unenrolled from your old MDM solution (default: `false`). Can only be configured for all teams (`default.yml`).
 - `enable_disk_encryption` specifies whether or not to enforce disk encryption on macOS, Windows, and Linux hosts (default: `false`).
 
 #### Example
@@ -214,6 +215,7 @@ controls:
     - path: ../lib/windows-script.ps1
     - path: ../lib/linux-script.sh
   windows_enabled_and_configured: true
+  windows_migration_enabled: true # Available in Fleet Premium
   enable_disk_encryption: true # Available in Fleet Premium
   macos_updates: # Available in Fleet Premium
     deadline: "2024-12-31"