Update reserved-capacity-overview.md

Author: oslake

articles/azure-sql/database/reserved-capacity-overview.md

@@ -67,7 +67,7 @@ vCore size flexibility helps you scale up or down within a performance tier and
 
 ## Limitation
 
-You cannot reserve DTU-based (basic, standard, or premium) databases in SQL Database.
+You cannot reserve serverless or DTU-based (basic, standard, or premium) databases in SQL Database.
 
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