Fork webpages

I'm looking for something a bit unusual. Say you are following the instructions for installing a software package (rl example: http://library.linode.com.../webmin/installing-webmin). Now you find out the instructions are outdated, or incomplete.

How do you keep your notes/additional instructions together with the original? Now you have two problems, your instructions and the original can be updated independently. What happens when the original is updated, or a new version of the software is released?

Wouldn't it be great if you could fork the webpage and update it (or even submit a pull request to the maintainer)?

Is there any practical way of working this way - or will I be stuck with a notetaker / blog / bunch of outdated textfiles?

A lot of questions - maybe one of you has the answer.