Update README.md

Add appropriate instructions on using the app, also give sample examples.

Look at the existing README.md file to understand the current structure. The issue asks for instructions on using the app and sample examples, but does not specify what those should be. Check the repository's code to see how the app is run and what inputs it expects. Then, update the README with clear setup and usage steps, and add example commands or screenshots.

索引モデルが issue の本文から書いたものです。