Jekyll seem to try to apply Liquid processing to software docs

[strogonoff]

With new customisation docs for metanorma-iso, causes build error on https://github.com/riboseinc/open.ribose.com/:

…was not properly terminated with regexp: /\}\}/ in /Volumes/Ribose/open.ribose.com/_projects/Metanorma/_software/metanorma-iso/docs/customisation.adoc              
bundler: failed to load command: jekyll (/Users/tony/.rvm/gems/ruby-2.4.4/bin/jekyll)       
Liquid::SyntaxError: Liquid syntax error (line 507): Variable '{{`, `{%`) unless you know what you're doing with them: they are how the pages are populated with metadata.

[strogonoff]

It seems like Jekyll::Document implicitly parses Liquid: https://www.rubydoc.info/github/jekyll/jekyll/Jekyll/Document, need to find a way to override that.