Documentation is great, but only when meaningful, and only when you can use it. Designing a website is not designing an operating system, in web design, you are dealing with a few files and assets. Don’t get me wrong, but when you need to put together 500 pages of diagrams, 23 hours of meetings and fill in a wiki-page with articles so you can make sure you properly nail down one single web page, you are in trouble.
Solution: create a single “pilot-project” document in google docs, word or plain text, use it as the product plan guide and focus your efforts in building the actual thing, not the paperwork and BS on how to build it.
Check out the most insightful and fun-to-read guide “The Nightmares of Web Design”: