configure-luma3ds: clarify boot.firm status

- As of B9S 1.4, missing boot.firm will also show a status notification LED. So that should be added to the message.
- Link Luma3DS boot.firm in case people don't have it for some reason (not all guide paths have people directly download it due to AIOs for MSET9 and skater, so we can't assume people have it)

Author: lilyuwuu

docs/_include/configure-luma3ds.md

@@ -1,5 +1,5 @@
 1. Your console should have booted into the Luma3DS configuration menu
     + Luma3DS configuration menu are settings for the Luma3DS custom firmware. Many of these settings may be useful for customization or debugging
     + For the purpose of this guide, **leave these options on the default settings** (do not check or uncheck anything)
-    + If your console shuts down when you try to power it on, ensure that you have copied `boot.firm` from the Luma3DS `.zip` to the root of your SD card
+    + If your console displays a white notification LED and shuts down when you try to power it on, ensure that you have [Luma3DS's `boot.firm`](https://github.com/LumaTeam/Luma3DS/releases/latest) on the root of SD card (inside `Luma3DSvX.X.X.zip`)
 1. Press (Start) to save and reboot