Stable version of docs has unstable banner

[dstansby]

📚 Documentation

On https://napari.org/stable/index.html there's a banner that says it's the unstable version of the docs, but I'm pretty sure that's the URL for the stable version

[psobolewskiPhD]

Thanks for reporting! We've been making changes under the hood to what is shown when and still working out some things with the banner and version switcher! Hopefully we can get it all resolved by the next release.

[jni]

I believe it should be resolved for the next release thanks to napari/napari.github.io#436. But we will only know on the next version deploy. @dstansby if you're curious about context see #836. We might want to go back and fix the existing deployments but that's relatively low return on investment.