📝 docs: add LICENSE.md file
📝 feat(launcher.py): add launcher script for retraction watch import
📝 chore: add requirements.txt file

The `.gitignore` file is updated to include a comprehensive list of files and directories that should be ignored by Git. This helps to keep the repository clean and avoid committing unnecessary files.

A `LICENSE.md` file is added to the repository to specify the licensing terms for the software. This file includes the copyright notice and permission conditions.

A `launcher.py` script is added to the repository. This script imports the necessary modules and runs the `import_logic` function from the `retraction_watch_import` module. The script is instrumented with the `longsight` library for monitoring and logging purposes.

A `requirements.txt` file is added to the repository to specify the dependencies required by the project

📦 chore(retraction_watch_import.py): add retraction_watch_import.py file
✨ feat(retraction_watch_import.py): add DAG for importing retractions
The retraction_watch_import.py file is added to the repository. It contains a DAG (Directed Acyclic Graph) definition for importing retractions. The DAG is scheduled to run daily and has a timeout of 16 hours. It imports necessary dependencies and defines a task for running the import process. The import process reads a CSV file, processes each row, and writes the retraction information to S3. The process includes extracting DOI and MD5, extracting fields from the CSV, generating an about block, creating a JSON template, and appending the retraction information to an index.