Add asdf

[a-b]

Asdf is a modern package manager written in pure shell. It's a direct substitution for many language-specific version managers and more.

List of supported packages: https://github.com/asdf-vm/asdf-plugins/tree/master/plugins

Getting started guide: https://asdf-vm.com/guide/getting-started.html

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: a-b / name: Al Berez (517e896820b9ed22c4a418c7941ee5a9616b68ec, 6f7cea5a6c4cee0c1f84c652e27337ac480a4ee6)