Added inline documentation and command line switches.

[matracey]

Description

Adds several features and improvements to the codebase, including inline documentation, command line switches, usage information and a print prompt option.

Changes Made

• Added JSDoc comments for better code clarity and maintainability.
• Added minimist for command-line argument parsing.
• Added the ability to print the prompt without calling the API, which is helpful if you don't have OpenAI API access.
• Added a new promptTemplate parameter to the index file, providing greater flexibility for customizing the prompt for ChatGPT.
• Added an "amend" (-a) command line switch to generate commit messages for the most recent commit instead of the index.
• Removed outdated notice from README and updated usage details.

These changes should make the codebase easier to understand and more versatile.

Screenshots (if appropriate)

N/A

Checklist

• [x] Code follows the style guide and best practices
• [x] Manual testing has been performed on all changes
• [x] Changes have been documented in the README file

[matracey]

Hey, wanted to follow up to see if you had a chance to test and review this? Would love to see this get merged into the main tool 😄

[BillChirico]

@RomanHotsiy Any update on a merge here?