Documenting useful packages, such as Match.jl and ConcurrentUtils.jl

I suggest documenting the availability of packages (useful for most), centrally somewhere, such as I did at:

For now I only added a few packages, and it may not be merged (I could only suggest as a draft).

Match.jl (for pattern matching similar to in Scala or newer Python versions), and Promises.jl (for promises, similar to in JavaScript). In both cases there are alternative packages implementing (even many in some cases, as happens for also for other packages), such as Rematch.jl and the newer ConcurrentUtils.jl

With this snowballing, add a new page. And please suggest the best alternative, in either case. At first I only only meant to add Match.jl as an example of something that is built-in syntax in other languages. I would like to trim the introduction to only the best packages, and elsewhere some good alternatives could be listed.