I wasn’t aware of these two tags for WooCommerce till I noticed one of my plugins was reporting as not tested with the latest version of WooCommerce. In your main plugin file, not the readme, you can add:
* WC requires at least: 2.5 * WC tested up to: 3.1
These declare the minimum version of WooCommerce that your plugin requires and the latest version it’s been tested against.
More information here.