cmnq_min_max_quantity.php

<?php
function wc_qty_add_product_field() {

	echo '<div class="options_group">';
	woocommerce_wp_text_input( 
		array( 
			'id'          => '_wc_min_qty_product', 
			'label'       => __( 'Minimum Quantity', 'woocommerce-max-quantity' ), 
			'placeholder' => '',
			'desc_tip'    => 'true',
			'description' => __( 'Optional. Set a minimum quantity limit allowed per order. Enter a number, 1 or greater.', 'woocommerce-max-quantity' ) 
		)
	);
	echo '</div>';

	echo '<div class="options_group">';
	woocommerce_wp_text_input( 
		array( 
			'id'          => '_wc_max_qty_product', 
			'label'       => __( 'Maximum Quantity', 'woocommerce-max-quantity' ), 
			'placeholder' => '',
			'desc_tip'    => 'true',
			'description' => __( 'Optional. Set a maximum quantity limit allowed per order. Enter a number, 1 or greater.', 'woocommerce-max-quantity' ) 
		)
	);
	echo '</div>';	
}
add_action( 'woocommerce_product_options_inventory_product_data', 'wc_qty_add_product_field' );
?>