You can include raw HTML, PDFs, plain-text, and other files in Forrest output by placing them in src/documentation/content and they will be copied over automatically. You can then link to them as normal, e.g. <link href="hello.pdf"/> and <link href="test1.html/>

You can also have sub-directories such as src/documentation/content/connectors which reflects your xdocs/connectors tree. The raw files will then end up beside your documents.