add rulehint entity

nodes.lua

@@ -384,3 +384,11 @@ if minetest.get_modpath("ethereal") then
         },
     })
 end
+
+minetest.register_entity("illuna:rulehint", {
+    visual = "sprite",
+    visual_size = {x=3,y=3},
+    collisionbox = {0},
+    physical = false,
+    textures = {"illuna_rulehint.png"},
+})