docs: Clarify disk resizing (#1383)

Author: Lenny4

readme.md

@@ -139,7 +139,7 @@ kubectl apply -f https://raw.githubusercontent.com/dockur/windows/refs/heads/mas
   ```
 
 > [!TIP]
-> This can also be used to resize the existing disk to a larger capacity without any data loss.
+> This can also be used to resize the existing disk to a larger capacity without any data loss. However you will need to [manually extend the disk partition](https://learn.microsoft.com/en-us/windows-server/storage/disk-management/extend-a-basic-volume?tabs=disk-management) since the added disk space will appear as unallocated.
 
 ### How do I share files with the host?