Because the code doesn't tell the whole story, Structurizr provides support for lightweight supplementary technical documentation. The documentation is a collection of Markdown or AsciiDoc files, one per section, which are rendered in the web browser. This content is uploaded in a workspace along with the software architecture model, which makes it easy to embed diagrams from that workspace. The code-based client libraries, Structurizr CLI - push command, and Structurizr DSL - !docs make it easy to import an existing folder of Markdown/AsciiDoc files into a workspace.
Please note that Structurizr's documentation feature may not render your Markdown/AsciiDoc in exactly the same way that other dedicated documentation tools will, and some features may not be supported. If you need full control over the look and feel of your documentation, you may be better to use an external tool (e.g. Asciidoctor, Hugo, Jekyll, etc) in conjunction with the iframe embed or image embed features.