Update README.md

Author: mlubin

README.md

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+**JuMPChance is no longer actively maintained. It is compatible with JuMP 0.18 and earlier.**
+
 JuMPChance (formerly CCJuMP) is an extension to [JuMP](https://github.com/JuliaOpt/JuMP.jl) for formulating and solving optimization problems with chance constraints (also known as probabilistic constraints). JuMPChance currently supports only a particular class of chance constraints involving affine combinations of jointly normal random variables, a classical formulation that's known to be efficiently solvable by using second-order conic programming (SOCP) (although JuMPChance also provides an outer-approximation algorithm which solves a sequence of linear problems).
 
 JuMPChance supports an extension of the classical model to distributionally robust (or ambiguous) chance constraints where the parameters of the normal distributions are known to fall in a symmetric interval or more general uncertainty set.