Update query_dsl.asciidoc

docs/reference/migration/migrate_2_0/query_dsl.asciidoc

@@ -25,7 +25,7 @@ be cacheable. Filter context is introduced by:
   aggregations or index aliases
 --
 
-As a result of this change, he `execution` option of the `terms` filter is now
+As a result of this change, the `execution` option of the `terms` filter is now
 deprecated and ignored if provided.
 
 ==== `or` and `and` now implemented via `bool`