Mapping guide: Update battery command

Oh my god its THAT old

src/en/space-station-14/mapping/guides/general-guide.md

@@ -83,7 +83,7 @@ Now to start creating maps follow the below steps:
 * If you want to test the lighting on your map without leaving the editor, use the "mapinit" command. Do **save before doing this** as it will ruin your map if you save after running this command.
 * Use https://affectedarc07.github.io/SS13WebMap/ to see most SS13 maps online
     - (https://game.ss13.moe/minimaps/images/maps/ for the /vg/ ones)
-* While testing your map, you might not want to be bothered to set up power each time. In that case, try: `forall with Battery do setbatterypercent $ID 100`
+* While testing your map, you might not want to be bothered to set up power each time. In that case, try: `> entities with Battery do "setbatterypercent $ID 100"`
 * Map auto-saving is enabled by default and goes to the server data directory every 10 minutes (cvar `mapping.autosave_interval`). You can turn it off with `toggleautosave [map id]` or change the `mapping.autosave` cvar.
 
 ## Mapping Actions