Hi there, awesomewm beginner here.
First of, thanks for this awesome project.

Description

When setting the brightness_widget settings to

brightness_widget({
  type = "icon_and_text",
  program = "brightnessctl",
})

the text displayed is not a percentage value but actual brightness value.
In my case it shows 14543 for e.g. and the max brightness value 19393.

Possible solution

To get the actual percentage, I think we can use brightnessctl -m | cut -d, f4 | tr -d %.

Happy to create a PR to fix this and get myself familiar with awesomewm.