Update minimum requirements for this plugin

Hi, please update minimum requirements in the installation tab. I was fighting with this plugin for 2 hours, just to find out that declared constants are different from information provided.

	const MIN_WPML = '4.2.8';
	const MIN_WPML_TM = '2.8.7';
	const MIN_WPML_ST = '2.10.6';
	const MIN_WOOCOMMERCE = '3.3.0';

So requirements should be:
WooCommerce 3.3.0 or later
WPML Multilingual CMS 4.2.8 or later
WPML String Translation 2.10.6 or later
WPML Translation Management 2.8.7 or later