Include files with shortcode

Insert some text from a file within the zola repo, and render the text as formatted in that file.
Tested with zola serve and zola build/ftp to remote site.

This works a little like the Jekyll {% include filename.html %}

As shortcodes require a parameter, this is a bit of a kludge, but works for both local build and remote deployment (tested remotely via FTP).

First, create an html or md file and save to /templates/shortcodes


* this is a bullet

Here is some random text

Call the shortcode in the page like this:

{% testing(variable=" ") %}
Text required to display shortcode but not actually displayed.
{% end %}