Transitioning solver interface

[blegat]

MathOptInterface.jl/docs/src/tutorials/mathprogbase.md

Lines 8 to 9 in 6380182

	Writing a solver interface in MathOptInterface is more work than the equivalent
	interface in MathProgBase.

should be more nuanced as explained in
https://github.com/jump-dev/MathOptInterface.jl/pull/1505/files#r683218384