We used to write thorough documentation. Thirty pages, contents page, screenshots of every admin screen, a glossary. It was genuinely good, and as far as we can tell almost nobody ever opened it. The questions arrived anyway, and they were the questions the document answered on page nine.
Why long documentation fails
A manual is written in the order the system is built. A person reads it in the order their problem occurs, which is never the same order. Faced with thirty pages and one specific question, most people email instead. The document was not too short or too unclear. It was the wrong shape.
People do not read documentation. They search it, once, under mild stress, for one answer.
The two pages that work
The first page is operational: where the site is hosted, where the domain is registered, where the logins live, who to contact, and what to do first if the site is down. Nothing about how to use the CMS. This page exists for the bad day, and on that day nobody wants to scroll.
The second page is the four or five things this client will actually do, each in three or four steps. Add a post. Change the hero image. Update the phone number. Add a team member. Not everything the system can do, just what this particular client asked for during the project.
The recording
Everything else becomes a five to eight minute screen recording, showing the same tasks being done in real time. It is faster to produce than written steps with screenshots, it is far easier to follow, and it survives interface updates better because it shows the shape of the task rather than the exact pixels.
We record with no branding and no reference to us, so an agency can put it in their own client portal without editing.
Writing it to be forwarded
The test for every piece of handover material is whether an agency can send it to their client unchanged. That rules out our name, our tone if it differs from theirs, screenshots with our staging URL visible, and any sentence that assumes the reader is technical.
Documentation written this way is shorter, cheaper to produce, and does more work, because it gets passed on instead of rewritten.