Enhance README file

[cheeZery]

• Document new CLI arguments
• Mention possibility to add own stuff underneath each dependency and its description
• Add example DEPENDENCIES.md file and link to it in README

[cheeZery]

• Describe possibility to add configuration files

[cheeZery]

• [Optional] Add tipps on how to improve depdoc experience (like custom scripts and post-install/post-update hooks)