How do I contribute to Guild Documentation?

How do I send a pull request with a proposed change to the Guild documentation?

I think there might be an error here: https://my.guild.ai/t/get-started-use-guild-in-a-project/203:

guild purge --started "before 30 days ago"

Should instead be

guild runs purge --started "before 30 days ago"

I would like to propose the correction but could not find the source of the documentation.