Minor frontend improvements

[arabcoders]

This pull request includes several changes to the README.md file, enhancements to the Config class, and various updates to the frontend components to add new features and improve user experience. The most important changes include adding a new instance title configuration, updating Docker and Docker Compose instructions, and enhancing the UI for better usability.

Documentation Updates:

• Updated Docker and Docker Compose instructions in README.md to reflect the latest usage and configuration options. [1] [2]
• Added new environment variable YTP_INSTANCE_TITLE to the configuration section in README.md.
• Added links to yt-dlp options and postprocessors in README.md.

Backend Enhancements:

• Added instance_title attribute to Config class in app/library/config.py to allow setting a custom title for the instance. [1] [2]

Frontend Improvements:

• Enhanced NewDownload.vue and TaskForm.vue components to include a "Convert to JSON" feature for CLI options and improved help text. [1] [2]
• Added a new convertCliOptions utility function in ui/utils/index.js to handle the conversion of CLI options to JSON format. [1] [2]

UI/UX Enhancements:

• Updated default.vue layout to display the instance title next to the application name and improved theme switching functionality. [1] [2]
• Improved responsive design for the index page to show the instance title on mobile devices.

These changes aim to improve the overall functionality and user experience of the application by providing better configuration options, clearer documentation, and enhanced UI components.