postinst is in yorick-doc 2.2.01+dfsg-2.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 | #!/bin/sh
set -e
case $1 in
  configure|reconfigure)
    if [ -e "/usr/share/yorick/i" ]; then
	update-yorickdoc --auto-now
    fi
    ;;
  triggered)
    update-yorickdoc --auto-now
    ;;
esac
 |