The diagram in your guide is a screenshot. Let's fix that.
Writing with its own tree, its own search and its own address, where the diagram on the page is the live one and a link in a sentence opens the detail behind a box.
What are you writing?
Step 01 of 03
Write it where the diagram already is
A tab can be prose, and it sits in the same strip as the drawing it describes, so the guide and the thing it is a guide to are one document with one address and one version.
Step 02 of 03
Write it with the blocks rather than with layout
Callouts, numbered procedures, tabs, code tabs, accordions, tiles, fields, trees and badges.
Every one of them is a blockquote with a marker on its first line, so it survives the visual editor and still reads as a quotation in any plain markdown renderer.
Step 03 of 03
Point a sentence at the box it is about
A link in the prose can open a stratum: the reader clicks the phrase, and the detail attached to that one shape opens with the diagram still on screen.
A callout can take the same link. Nobody has to work out which paragraph belongs to which box.
Your next step
Then it does not go stale on its own
There is no screenshot to re-take and no second document to remember. Editing the drawing changes what the guide shows, because the guide is looking at the drawing rather than at a picture of one.