Merge pull request #23503 from WilliamAntonRohm/issue-7880

sql-docs/issues/7880 -- clarify optional

Author: PRMerger18

docs/t-sql/functions/last-value-transact-sql.md

@@ -33,7 +33,7 @@ Returns the last value in an ordered set of values.
 
 ```syntaxsql
 LAST_VALUE ( [ scalar_expression ] )  [ IGNORE NULLS | RESPECT NULLS ]
-    OVER ( [ partition_by_clause ] order_by_clause rows_range_clause )
+    OVER ( [ partition_by_clause ] order_by_clause [ rows_range_clause ] )
 ```
 
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