add iso9660 (#4400)

README.md

@@ -1056,6 +1056,7 @@ _Libraries for handling files and file systems._
 - [gofs](https://github.com/no-src/gofs) - A cross-platform real-time file synchronization tool out of the box.
 - [gut/yos](https://github.com/1set/gut) - Simple and reliable package for file operations like copy/move/diff/list on files, directories and symbolic links.
 - [higgs](https://github.com/dastoori/higgs) - A tiny cross-platform Go library to hide/unhide files and directories.
+- [iso9660](https://github.com/kdomanski/iso9660) - A package for reading and creating ISO9660 disk images
 - [notify](https://github.com/rjeczalik/notify) - File system event notification library with simple API, similar to os/signal.
 - [opc](https://github.com/qmuntal/opc) - Load Open Packaging Conventions (OPC) files for Go.
 - [parquet](https://github.com/parsyl/parquet) - Read and write [parquet](https://parquet.apache.org) files.