ShortCode: list products by taxonomy

This is a slight modification to the built-in Woo shortcode called product_categories

It has been modified in two ways:

1. It takes a second arguement to specify the taxonomy to use, not just the product category;
2. the get_terms() call was updated to be WordPress 4.5 compliant.

To use

Put the shortcode PHP file somewhere and reference it, or copy and paste the contents into your functions.php file. Then call the shortcode using [product_by_taxonomy] and options as described on this page, with the additional arguement taxonomy to specify the taxonomy to use.