Update outdated doc link

[PallHaraldsson]

https://non-contradiction.github.io/JuliaCall/index.html

to the right on the main github page doesn't work, and it's not a good look.

I want to promote this package, now that it has migrated (and for sure working again?) and checked and this seems to be the replacement link:
https://juliainterop.github.io/JuliaCall/

Currently Julia v0.6.x, Julia v1.0.x, and Julia v1.1 are all supported by JuliaCall.

That's outdated, Please add relevant current version info, and drop old versions if no longer working in the docs.

I believe the package works; including from conda? This should be an easy issue, so I'll delay a bit pointing to this package. Any other URL I should point to?