Remove version specific docs

[EwoutH]

Update version references in docs to be more generic, avoiding the need to update them with each release.

Also, SolaraViz has been stable and well-tested through the Mesa 3.0.x series. Remove the experimental warnings and version-specific notes from documentation, as it is now a stable component of Mesa 3.1.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
BoltzmannWealth	small	🔵 +2.8% [+1.3%, +4.4%]	🔵 -0.8% [-1.0%, -0.5%]
BoltzmannWealth	large	🔵 -1.4% [-4.2%, +0.3%]	🔵 +3.7% [+1.9%, +5.2%]
Schelling	small	🔵 -1.0% [-1.3%, -0.8%]	🔵 -1.8% [-1.9%, -1.7%]
Schelling	large	🔵 -0.5% [-0.8%, -0.2%]	🔵 -1.0% [-1.6%, -0.2%]
WolfSheep	small	🔵 -1.8% [-2.0%, -1.6%]	🔵 -0.6% [-0.8%, -0.4%]
WolfSheep	large	🔵 -0.4% [-1.1%, +0.2%]	🔵 +2.7% [+1.3%, +4.1%]
BoidFlockers	small	🔵 +0.3% [-0.2%, +0.7%]	🔵 +0.5% [+0.3%, +0.7%]
BoidFlockers	large	🔵 +0.1% [-0.5%, +0.7%]	🔵 +0.7% [+0.4%, +1.0%]

[quaquel]

I am not sure about this removal. Yes solara as basis is fine, but I am not convinced yet fully by the api side of things.

[EwoutH]

We can't keep it experimental forever right? Maybe we need to commit to the current API and move to 4.0 if we want to change / overhaul it again.

[quaquel]

Nothing has changed fundamentally compared to where we were when releasing 3.0. So, all the reasons we had back then for keeping it experimental still stand. The passing of time alone is not a reason for making something suddenly stable.

In fact, the recent bugs we have found underline the immaturity of the code, further validating this original choice to keep it experimental.

[EwoutH]

Not sure if I fully align on the time passing statement, but in general sentiment I agree.

Shall we change the note to simply say 3.x?

Note: SolaraViz is experimental and still in active development in Mesa 3.x. While we attempt to minimize them, there might be API breaking changes in minor releases.

[quaquel]

see my earlier comment

[quaquel]

fine except the solara experimental stuff.