* chore(plugins/brew): rename buf alias to bfu

The alias `buf` collides with the protobuf tooling (buf)[https://buf.build/].

This commit renames the `buf` alias to `bfu` (`brew upgrade --formula`) so its semantically more aligned with `bcu` (`brew upgrade --cask`) as well as to avoid command collision especially with existing scripts that refers to `buf` as the tool and not the alias.

* chore(brew): updated README.md

Updated README to reflect renamed alias (`buf` -> `bfu`)
Co-authored-by: Robby Russell <robby@planetargon.com>