Package-json-to-readme is a command-line tool that automatically generates a basic README.md file from the contents of a package.json file. It's designed for Node.js and io.js developers who want to quickly create a boilerplate README with essential information like project name, description, installation instructions, and license details. The tool can also add features like Travis CI badges and test output, making it ideal for developers looking to streamline their documentation process for npm modules.