Apply suggestions from code review

Author: Vaibhavdixit02

docs/src/getting_started/fit_simulation.md

@@ -311,9 +311,9 @@ More details about callbacks in Optimization.jl can be found
 [here](https://docs.sciml.ai/Optimization/stable/API/solve/).
 
 ```@example odefit
-function callback(p, l)
+function callback(state, l)
     display(l)
-    newprob = remake(prob, p = p)
+    newprob = remake(prob, p = state.u)
     sol = solve(newprob, saveat = 1)
     plt = plot(sol, ylim = (0, 6), label = ["Current x Prediction" "Current y Prediction"])
     scatter!(plt, t_data, xy_data', label = ["x Data" "y Data"])