docs: add 3ds system transfer warning

docs/en_US/install/3ds.md

@@ -1,5 +1,10 @@
 # 3DS/2DS Family
 
+<div class="tip red">
+	<strong>CAUTION:</strong>
+	SYSTEM TRANSFERS ARE NOT CURRENTLY SUPPORTED BY OUR SERVERS. ATTEMPTING TO PERFORM A SYSTEM TRANSFER MAY PREVENT YOU FROM BEING ABLE TO GO ONLINE IN THE FUTURE. SUPPORT FOR SYSTEM TRANSFERS IS IN DEVELOPMENT.
+</div>
+
 <div class="tip">
 	ℹ️ This guide assumes that you have a <b>Homebrewed System running the latest version of Luma3DS (13+)</b>, if you don't please follow this <a href="https://3ds.hacks.guide/" target="_blank">guide</a> on how to homebrew your system first.
 </div>