I'm currently at a contract position and am looking to add to the documentation of the projects I worked on, to assist the next hiree taking over my projects.

The documentation I received was overly technical (i.e. references code right away, references replacing certain values on certain lines, no high level description at all)

How do I write documentation in simple plain English that is of actual benefit without looking sloppy? I find it difficult in areas such as outlining a system's flaws without coming off as judgmental, but still emphasize the severity of how detrimental some of the flaws are.