message: Document techdocs svg_object limitation
  Currently it is not possible to use the PlantUML format 'svg_object' as this
  makes it possible for bad actors to inject malicious content into documentation.
  This change documents this limitation under the troubleshooting section of the
  techdocs feature.
diff: @@ -55,3 +55,20 @@ INFO - Start watching changes
  [I 210115 19:00:45 handlers:64] Start detecting changes
  INFO - Start detecting changes
  ```
  +
  +## PlantUML with `svg_object` doesn't render
  +
  +The [plantuml-markdown](https://pypi.org/project/plantuml-markdown/) MkDocs
  +plugin available in
  +[`mkdocs-techdocs-core`](https://github.com/backstage/mkdocs-techdocs-core)
  +supports different formats for rendering diagrams. TechDocs does however not
  +support all of them.
  +
  +The `svg_object` format renders a diagram as an HTML `<object>` tag but this is
  +not allowed as it enables bad actors to inject malicious content into
  +documentation pages. See
  +[CVE-2021-32661](https://github.com/advisories/GHSA-gg96-f8wr-p89f) for more
  +details.
  +
  +Instead use `svg_inline` which renders as an `<svg>` tag and provides the same
  +benefits as `svg_object`.
  