fix tutorial

Author: BatyLeo

docs/src/tutorials/warcraft.jl

@@ -70,7 +70,7 @@ opt_state = Flux.setup(Adam(1e-3), model)
 loss_history = Float64[]
 for epoch in 1:50
     val, grads = Flux.withgradient(model) do m
-        sum(loss(m(sample.x), sample.y) for sample in train_dataset) / length(train_dataset)
+        sum(loss(m(x), y_true) for (; x, y_true) in train_dataset) / length(train_dataset)
     end
     Flux.update!(opt_state, model, grads[1])
     push!(loss_history, val)