Fix typo

Author: changeworld

articles/azure-sql/database/automatic-tuning-enable.md

@@ -76,7 +76,7 @@ Please note that DROP_INDEX option at this time is not compatible with applicati
 
 Once you have selected your desired configuration, click **Apply**.
 
-### Rest API
+### REST API
 
 To find out more about using a REST API to enable automatic tuning on a single database, see [Azure SQL Database automatic tuning UPDATE and GET HTTP methods](/rest/api/sql/databaseautomatictuning).