What is prometheus-node-exporter-lua-textfile

In the list of software packages related to Prometheus I can see one named "prometheus-node-exporter-lua-textfile"

I have been searching for some documentation on this package, but cannot manage.

Can someone explain what is this used for, and supply any link to any relevant documentation or example?

Device details below:

Model Linksys WRT1900AC
Firmware Version OpenWrt 19.07.3 r11063-85e04e9f46 / LuCI openwrt-19.07 branch git-20.136.49537-fb2f363|