A Jekyll's liquid tag plugin to include a file from its path relative to Jekyll's source folder. Why? Because Jekyll's built-in include tag does not support including files outside of _includes folder.
Syntax: {% include_absolute path %}
Copy include_absolute.rb into /_plugins.
With this plugin you can include only a file.
{% include_absolute '../../folder/outside/jekyll/foo.html' %}
{% include_absolute 'other/folder/bar.js' %}
Or include the file and pass parameters to it.
{% include_absolute '../../folder/outside/jekyll/foo.html' param1='yes' param2='green' %}