You can either :
download the phar version 1.2.1 that has all required (as well as some optional) dependencies of UmlWriter bundled in a single file.
install latest version with composer, as follow:
composer require bartlett/umlwriter ^1.2
The documentation for UmlWriter 1.2 is available in English to read it online or download to read it later (multiple formats).
AsciiDoc source code are available on
docs folder of the repository.
This handler is licensed under the BSD-3-clauses License - see the
LICENSE file for details