Docs: Expand CLI Usage Documentation

[nathanschmid08]

Description

As the Avenx CLI grows, we need dedicated documentation detailing all available commands (e.g., avenx build, avenx dev, etc.). This should serve as a reference manual for developers using the command line interface.

Acceptance Criteria

• Create a cli-reference.md in the docs/ directory.
• List all commands with their flags, options, and descriptions.
• Provide simple usage examples for each command.