Contributing guide is somewhat outdated

[christopher-dG]

The recommended tutorials are fairly old, and I have not watched them in depth but there may be plenty of code in there which no longer works. Perhaps refer to this playlist instead?

Dead link:

New libraries should be developed as packages.

Perhaps this link should point to Pkg.jl now instead:

Julia has a built-in package manager

This is more or less outside the "outdated" point, but immediately seeing the warning that says "this is unreleased and in-development" can be misleading and intimidating if you don't realize that it's not the stable docs (I think this applies to all the documentation links):

The Julia documentation covers the language and core library features, and is searchable.

Another dead link:

The Julia manual provides instructions on creating Julia packages

[laborg]

CONTRIBUTING.md has been updated many times since this issue was filed. I've checked and couldn't find any dead links in it anymore.