Fix: use correct wording for customers

Author: runarobbaile

changelog/api.mdx

@@ -9,7 +9,7 @@ description: "Changelog of all major API updates, new features, removals, and im
 
 Following Bulgaria's move to adopt the Euro **(1 January 2026)**, we have removed FX support for BGN. Please refer to the Currencies [API reference](/reference/currencies) to view our currency support for top ups and FX.
 
-All affected customer were notified ahead of time and any remaining balance will have been converted automatically to `EUR`.
+All affected customers were notified ahead of time and any remaining balance have been converted automatically to `EUR`.
 
 </Update>