Blog post about editable packages is deprecated

When looking for a reference about editable packages, I found this nice blog post: https://blog.conan.io/2019/02/04/New-conan-release-1-12.html

However, it uses the old command `conan link`, which is deprecated now.

I think we could update that blog post with a warning message, like:

"Conan link command has been deprecated since version x.y.z, please a look on its new format "