POMDPX Documentation Site Unavailable

The site that previously hosted the POMDPX file specification documentation ([bigbird.comp.nus.edu.sg](https://bigbird.comp.nus.edu.sg/pmwiki/farm/appl/index.php?n=Main.PomdpXDocumentation)) appears to be down.

I was able to access an archived version through the Wayback Machine: [Archived POMDPX Documentation](https://web.archive.org/web/20230131145637/https://bigbird.comp.nus.edu.sg/pmwiki/farm/appl/index.php?n=Main.PomdpXDocumentation).

Since this documentation is important for users of POMDPXFiles.jl, it may be worth mirroring the relevant content somewhere more stable (e.g., in the JuliaPOMDP organization, GitHub wiki, or a separate markdown file in this repo). Are there any existing backups of this documentation, or should we consider extracting and hosting the information elsewhere?