[docs] Update done items on roadmap

[odow]

Implemented in Gurobi: jump-dev/Gurobi.jl#392
Documentation at the JuMP level already exists: https://jump.dev/JuMP.jl/stable/solutions/#Multiple-solutions

[joaquimg]

🎉

[codecov]

Codecov Report

Merging #2453 (f22247b) into master (e25dd20) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2453   +/-   ##
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  Coverage   92.21%   92.21%           
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  Files          43       43           
  Lines        4637     4637           
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  Hits         4276     4276           
  Misses        361      361           

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[mlubin]

I'm a bit confused about the documentation. Are all solutions returned by a solver guaranteed to be optimal? I know that some solvers can return suboptimal solutions found during the solve.

[odow]

Hmm. Yeah I don't think the documentation should say an_optimal_solution. The solution in result = 1 is probably the optimal solution, and the others are sub-optimal, feasible solutions. You could figure that out by looking at the objective value?

[odow]

So does this count as done now?