Download docker-org-export
script and add it to your PATH.
You can transform your org-file to html like this:
docker-org-export index.org
There is seqdiag
support, so you can use this in your source code:
#+begin_src seqdiag :file wap_success_seqdiag.png
seqdiag {
A -> B [label="Test edge"];
}
#+end_src