Convert MD GFM to FB2

Markdown (MD) is a lightweight markup language with a file extension MD, commonly used for formatting readme files, documentation, and comments in GitHub repositories. GitHub-Flavored Markdown (GFM) extends the original Markdown's capabilities, adding features like tables, task lists, and auto-linking URLs. Markdown's simplicity and effectiveness in creating formatted text using a plain text editor made it widely adopted in the developer community. GFM, in particular, is optimized for use on GitHub, enhancing collaboration and code documentation.

The FB2 file extension stands for FictionBook 2.0, a popular XML-based eBook format. Initially developed in Russia for easy parsing and conversion across different eBook readers, it preserves metadata and structure effectively. FB2 is mainly used for fictional literature, allowing detailed descriptions of text formatting, titles, and subtitles, which enhances the user reading experience. Its open-standard nature ensures broad compatibility and ease of modification, making it a preferred choice in digital publishing.