WordPress plugin to add category description to end of the_content

add_category_description_to_content.php

<?php
/*
Plugin Name: Add category description to content
Plugin URI:  https://oikos.digital/
Description: Adds the category description to the end of the_content()
Version:     1.0
Author:      Ross Wintle/Oikos
Author URI:  https://oikos.digital/
 */

if(! function_exists( 'oikos_add_cat_desc') ) {
  function id_add_cat_desc($content) {
    global $post;
    $categories = get_the_category( $post->ID );
    if (is_array($categories) && !empty($categories)) {
      $cat = current($categories);
      $content = $content . $cat->description;
    }
  return $content;
  }
}
add_filter( 'the_content', oikos_add_cat_desc, 1, 1);