retail-roms: Add DSiWare section

pages/_en-US/ds-index/retail-roms.md

@@ -138,3 +138,24 @@ In terms of the system identifiers:
 ### DSi Enhanced:
 
 Games with "DSi Enhanced" functionality are games that take advantage of some aspect of the DSi's hardware while still remaining compatible with the DS Phat/Lite. These games are marked as `TWL` but still say "Nintendo DS" instead of "Nintendo DSi" on the label.
+
+### DSiWare:
+
+DSiWare are digital games and apps which we're downloadable from the DSi Shop, to then launch from the DSi System Menu.
+    - Examples are:
+	    - Art Style Series
+	    - Flipnote Studio
+		- G.G Series
+		- The Legend of Zelda: Four Swords: Anniversary Edition
+		- Nintendo DSi Browser
+		- Shantae: Risky's Revenge
+		- EA's Sudoku
+	- Most DSiWare titles could also be downloaded via the 3DS eShop.
+	- DSiWare titles are no longer downloadable, due to both shops being closed.
+
+DSiWare can only be run from the internal system memory, unless when using **TW**i**L**ight Menu++ to launch them from the DSi/3DS SD Card or flashcard.
+    - By using a flashcard, some DSiWare titles can be run on a DS or DS Lite console.
+
+Every DSiWare/DSi system application (except for the System Menu) disables Slot-1 (aka the DS game card slot) access, preventing access to what's stored on the game card or even the flashcard.
+    - This means developers could not add support for DS games as a way of accessing hidden features within DSiWare titles.
+    - This also means homebrew apps (which would be run via exploited DSiWare apps) such as GodMode9**i** cannot dump/extract ROMs from DS game cards, unless when running via Unlaunch.