Gaussion Processes : added navbar workflow

[jeetsuthar]

We are adding this to all Turing satellite packages! See here - https://github.com/TuringLang/turinglang.github.io/blob/main/assets/scripts/README.md

We also announced this navigation bar in our Turing slack's general channel!

[willtebbutt]

Sorry, it's not clear to me what the purpose of this is. Can I see an example of what this looks like in the existing docs somewhere before we commit to it in the JuliaGPs ecosystem (which is separate from the Turing.jl ecosystem)

[yebai]

I manually added a commit to the master (AbstractGPs and ApproximateGPs, created by the Turing team), which is already visible — sorry for forgetting to go through a PR. I was not aware of these PRs.

It adds a top navigation menu, making navigating between different packages easier. The menu content can be adapted to suit the JuliaGP ecosystem.