Download package in julia

Hi, I want to download kNN package in julia. The link is KNN · Julia Packages
My code is

using Pkg

And I got error

  • kNN (not found in project, manifest or registry)

But I can download other packages successfully. So how to download kNN successfully? Thank you in advance!

I think the function requires PackageSpec: 12. API Reference · Pkg.jl
But this should work: ]add kNN.

Edit: Actually I think the problem is the package is not registered. The Github website also suggests to use a package that superseded this one: GitHub - KristofferC/NearestNeighbors.jl: High performance nearest neighbor data structures and algorithms for Julia.
Like so ]add NearestNeighbors. Because that package is registered.