Multiple authors in feature card

[lukavdplas]

Show "and others" in the featured notebook card when it has more than one author listed (close https://github.com/fonsp/Pluto.jl/issues/2719)

For instance, if the first notebook would have more authors, it would look like this:

[github-actions[bot]]

Try this Pull Request!

Open Julia and type:

  julia> import Pkg
  julia> Pkg.activate(temp=true)
  julia> Pkg.add(url="https://github.com/lukavdplas/Pluto.jl", rev="multiple-authors-in-feature-card")
  julia> using Pluto

[fonsp]

Wooohooo thanks!!