Add instructions for installation with aqua

[nikolay]

I've been using aqua and recently asked the config-file-validator to be added to the registry. Given aqua is multi-platform and could easily be used within a GitHub Action, doing so would add value to both projects.

[suzuki-shunsuke]

aqua is a CLI Version Manager.
aqua's Standard Registry has supported this tool at v4.58.0.

• Add support for github.com/Boeing/config-file-validator/cmd/validator aquaproj/aqua-registry#16019
• feat: add Boeing/config-file-validator aquaproj/aqua-registry#16027

You can install this tool using aqua.

aqua init # Create aqua.yaml
aqua g -i Boeing/config-file-validator # Add Boeing/config-file-validator to aqua.yaml
aqua i # Install tools

I created a pull request.

• docs: add the install guide using aqua #58

[kehoecj]

Thank you @nikolay for the suggestion and @suzuki-shunsuke for the PR! Aqua looks like an awesome tool.

[nikolay]

@kehoecj It is way more than what it seems on the surface!