docbook-xsl binary package in Ubuntu Bionic armhf

 These are modular XSL stylesheets for processing documents composed
 with the DocBook XML DTD and its derivatives ("Simplified" DocBook
 XML, JRefEntry DTD, etc.).
 .
 The stylesheets provide XSLT transformations for (X)HTML, WordML, HTML Help,
 JavaHelp, Man page (nroff), Website, Eclipse Platform Help file and XSL
 Formatting Object (XSL-FO) output. The latter can be further processed to
 a number of print formats using FOP or TeX-based tools.
 .
 The stylesheets are modular in the sense that you can extend and, to some
 extent, customize them. The documentation is included in a separate package.

Source package