add comment.

mods/bg_api/wrappers.lua

@@ -36,6 +36,7 @@ local events = blockgame.events.namespace("api")
 
 function blockgame.register_node (name, def, modname)
 	-- TODO: take full name and then extract modname and base name from that, that'll probably be easier to maintain.
+	-- (if no modname is provided, still assume it like what is being done currently.)
 	local modname = modname or minetest.get_current_modname()
 	local full_name = modname .. ":" .. name