hide first block output in kfold example

[snotskie]

In https://snotskie.github.io/EpistemicNetworkAnalysis.jl/latest/examples/cross-validation/, the first block should have this line added to it:

return nothing # hide

to suppress the Pkg log output

[snotskie]

also add Tutorial and Final Product or etc. H2s

[snotskie]

https://github.com/snotskie/EpistemicNetworkAnalysis.jl/commit/0655b3b577c05731373976f16fc9b90b971db103

the trick is to run docs make.jl twice, once to grab the precompile, once to run without it outputing a message