Package tutorials

[abelsiqueira]

The following packages need an "Introduction to" tutorial:

• LinearOperators.jl (Create tutorial Introduction to LinearOperators.jl #1)
• Krylov.jl
• NLPModels.jl
• SolverBenchmark.jl
• JSOSolvers.jl
• JSOSuite.jl

[dpo]

SolverBenchmark already has a pretty good tutorial in the docs. Should it be extracted and moved here? Then we could add a pointer to this repo in the SolverBenchmark docs.

NLPModels also has a good tutorial (that could be expanded).

[abelsiqueira]

Yes, I'm thinking most tutorials in the docs should be moved here.