Add documentation contribution of multi/nonlocal stability by Attractors.jl

[Datseris]

We have discussed this on Slack some time ago! cc @TorkelE @ChrisRackauckas

[ChrisRackauckas]

I think this might fit better as an example instead of a tutorial?

[Datseris]

I've put it as a tutorial because the bifurcation diagrams page was also a tutorial. This functionality targets similar research questions as bifurcation diagrams do. But I'm happy to put it as an example instead.

[ChrisRackauckas]

The bifurcation diagrams should also be an example. We'll probably address that in the doc overhaul #3505. I guess for now whatever let's slap it in there and adjust when we do the others.

[ChrisRackauckas]

Build failure.

[Datseris]

Have forgotten to add the package to the docs/Project.toml. Should work now.