[feature](website): create a install doc of harbor-cli

## Problem
What problem does this feature solve?
create a install doc for harbor-cli

## Proposed Solution
https://just.systems/man/en/packages.html - something like this.

Use the proposed just.systems package-installation page as the reference for the harbor-cli installation documentation. Review the repository's existing website or documentation structure to choose the destination, then add the installation instructions and confirm that the document clearly explains how to install harbor-cli.

Written by the indexing model from the issue text.