Add the product's short description to the Mix and Match table

functions.php

add_action( 'woocommerce_mnm_row_item_description', 'mnm_add_short_description', 15 );

function mnm_add_short_description( $mnm_product ){
	if ( ! $mnm_product->post->post_excerpt ) {
		return;
	}

	?>
	<div itemprop="description">
		<?php echo apply_filters( 'woocommerce_short_description', $mnm_product->post->post_excerpt ) ?>
	</div>
<?php
}