github pages is building jekyll in safe mode. It means custom plugins in _plugins directory are ignored because of overriding config value of _plugins dirctory.
# Options which GitHub Pages sets, regardless of the user-specified value## The following values are also overridden by GitHub Pages, but are not# overridden locally, for practical purposes:# * source# * destination# * jailed# * verbose# * incremental# * GH_ENVOVERRIDES={"lsi"=>false,"safe"=>true,"plugins"=>SecureRandom.hex,"plugins_dir"=>SecureRandom.hex,"whitelist"=>PLUGIN_WHITELIST,"highlighter"=>"rouge","kramdown"=>{"template"=>"","math_engine"=>"mathjax","syntax_highlighter"=>"rouge"},"gist"=>{"noscript"=>false}}.freeze
how can i apply custom filter? jekyll's description is little bor ambigous.