Update changelog.txt

Author: Matt Allan

changelog.txt

@@ -1,7 +1,7 @@
 *** WooCommerce Subscriptions Core Changelog ***
 
 = 7.1.2 - 2024-xx-xx =
-* Update - Show "FREE" instead of 0 when there is no shipping cost in the recurring totals section of the Cart and Checkout blocks.
+* Update - Show "FREE" instead of 0 when there is no shipping cost in the recurring totals section of the Cart and Checkout blocks (requires WooCommerce 9.0+).
 
 = 7.1.1 - 2024-05-09 =
 * Fix - Resolved an issue that caused "WC_DateTime could not be converted to int" warnings to occur on non-hpos sites while editing a subscription.