PLT - append references in Solvers and Objective HTML descriptions

[Badr-MOUFAD]

Follow up of #556 #543,
to append solver and objective references to the shown description.

fixes #570 and accordingly addresses #120

[mathurinm]

Does it fix 570 ? I think it works already, no?

[Badr-MOUFAD]

Right @mathurinm!
It is just because we have a dedicated parameter references to put academic references?

Should we drop it in favor of docstrings to provide descriptions?

[mathurinm]

Yes I'd go this way : it's the chosen way to display the information, and so we don't want to store it in two places. I have started it on the Lasso benchmark for example. benchopt/benchmark_lasso#133