Update release notes

Author: RafaelKayumov

RELEASE-NOTES.txt

@@ -16,6 +16,7 @@
 - [*] Watch app: Fixed connection issue upon fresh install [https://github.com/woocommerce/woocommerce-ios/pull/15867]
 - [Internal] Shipping Labels: Optimize requests for syncing countries [https://github.com/woocommerce/woocommerce-ios/pull/15875]
 - [*] Shipping Labels: Display label size from account settings as default [https://github.com/woocommerce/woocommerce-ios/pull/15873]
+- [*] Shipping Labels: Ensured customs form validation enforces non-zero product weight to fix shipping rate loading failure. [https://github.com/woocommerce/woocommerce-ios/pull/15927]
 
 22.7
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