Update release notes

Author: itsmeichigo

RELEASE-NOTES.txt

@@ -4,6 +4,7 @@
 22.9
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 - [*] Order List: New orders made through Point of Sale are now filterable via the Order List filters menu [https://github.com/woocommerce/woocommerce-ios/pull/15910]
+- [*] Shipping Labels: Display base rate on selected shipping service cards [https://github.com/woocommerce/woocommerce-ios/pull/15916]
 
 22.8
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