Fix DELETE clause in MERGE USING grammar

h2/src/docsrc/help/help.csv

@@ -68,7 +68,7 @@ UPDATE PERSON P SET NAME=(SELECT A.NAME FROM ADDRESS A WHERE A.ID=P.ID);
 "
 
 "Commands (DML)","DELETE","
-DELETE [ TOP term ] FROM tableName [ WHERE expression ] [ LIMIT term ]
+DELETE [ TOP term ] FROM tableName deleteSearchCondition
 ","
 Deletes rows form a table.
 If TOP or LIMIT is specified, at most the specified number of rows are deleted (no limit if null or smaller than zero).
@@ -124,7 +124,7 @@ MERGE INTO targetTableName [ [AS] targetAlias]
 USING { ( select ) | sourceTableName }[ [AS] sourceAlias ]
 ON ( expression )
 [ WHEN MATCHED THEN
-    [ UPDATE SET setClauseList ] [ delete ] ]
+    [ UPDATE SET setClauseList ] [ DELETE deleteSearchCondition ] ]
 [ WHEN NOT MATCHED THEN INSERT insertColumnsAndSource ]
 ","
 Updates or deletes existing rows, and insert rows that don't exist. The ON clause
@@ -132,8 +132,9 @@ specifies the matching column expression and must be specified. If more than one
 is updated per input row, an exception is thrown.
 If the source data contains duplicate rows (specifically those columns used in the
 row matching ON clause), then an exception is thrown to prevent two updates applying
-to the same target row. The embedded update, delete or insert statements can not re-specify
-the target table name.
+to the same target row.
+WHEN MATCHED THEN or WHEN NOT MATCHED THEN clauses or both of them in any order should be specified.
+If WHEN MATCHED THEN is specified it should contain UPDATE or DELETE clauses of both of them.
 ","
 MERGE INTO TARGET_TABLE AS T USING SOURCE_TABLE AS S
     ON (T.ID = S.ID)
@@ -2247,6 +2248,14 @@ SELECT CAST(0 AS DOUBLE)
 SELECT -1.4e-10
 "
 
+"Other Grammar","Delete search condition","
+[ WHERE expression ] [ LIMIT term ]
+","
+Search condition for DELETE statement.
+","
+WHERE ID = 2
+"
+
 "Other Grammar","Digit","
 0-9
 ","