Create Custom Post Type and Custom Taxonomy

functions.php

/*////////////////////////////////////////////////
//
//	Custom Taxonomy -> Guide Categories
//	Custom Post Type -> Guide
//
////////////////////////////////////////////////*/
function guide_taxonomy() {
	register_taxonomy(
			'guide_category',	//The name of the taxonomy. Name should be in slug form (must not contain capital letters or spaces).
			'guide',			//post type name
			array(
					'hierarchical' => true,
					'label' => 'Guide Categories',  //Display name
					'show_admin_column' => true,
					'query_var' => true,
                                        'show_in_rest' => true, //Enabling guide categories Gutenberg editor.
					'rewrite' => array(
							'slug' => 'guide', // This controls the base slug that will display before each term
							'with_front' => false // Don't display the category base before
					)
			)
	);
}
add_action( 'init', 'guide_taxonomy');

function create_guide_post_type() {
	$labels = array(
			'name' => esc_html__( 'Guides', 'pmo' ),
			'singular_name' => esc_html__( 'Guide', 'pmo' ),
			'add_new_item' => esc_html__( 'Add New Guide', 'pmo' ),
	);
	$args = array(
			'labels' => $labels,
			'public' => true,
			'has_archive' => true,
			'rewrite' => array('slug' => 'guides'),
			'menu_icon' => 'dashicons-book-alt',
			'supports' => array('title','editor','thumbnail','excerpt','page-attributes'),
			'publicly_queryable' => true,
			'show_in_rest' => true, //Enabling Gutenberg editor. No plugin needed for classic editor!
	);
	register_post_type('guide', $args);
}
add_action('init', 'create_guide_post_type');