Update installing-dsi.md

Author: RocketRobz

pages/_en-US/twilightmenu/installing-dsi.md

@@ -17,6 +17,7 @@ If you do not already have a way to run homebrew on your DSi, follow [dsi.cfw.gu
 1. Extract `TWiLightMenu-DSi.7z`
 1. Copy the `_nds` folder to your SD card root
 1. Copy the `BOOT.NDS` file to your SD card root
+    - If you've come from dsi.cfw.guide, and there's already a `BOOT.NDS` file on the SD card root, then overwrite it when asked to
 1. Copy the `roms` folder to your SD card root
 1. **hiyaCFW users:** Copy the `title` folder to your SD card root