Fix typo in README (#175)

Author: odow

README.md

@@ -48,7 +48,7 @@ the choice of solution algorithm.
 
 Documentation is available in the JuMP documentation. There are sections on
 [setting a vector-valued objective](https://jump.dev/JuMP.jl/stable/manual/objective/#Set-a-vector-valued-objective)
-and [working wtih multiple solutions](https://jump.dev/JuMP.jl/stable/manual/solutions/#Multiple-solutions).
+and [working with multiple solutions](https://jump.dev/JuMP.jl/stable/manual/solutions/#Multiple-solutions).
 For worked examples, see the [Simple multi-objective examples](https://jump.dev/JuMP.jl/stable/tutorials/linear/multi_objective_examples/)
 tutorial in the JuMP documentation. A larger example is the
 [Multi-objective knapsack](https://jump.dev/JuMP.jl/stable/tutorials/linear/multi_objective_knapsack/)