fix(doc): add info about objects types that allowed for export (#10627)

Co-authored-by: Ivan Blinkov <[email protected]>

Author: ulya-sidorina

ydb/docs/en/core/reference/ydb-cli/export-import/_includes/s3_export.md

@@ -6,6 +6,16 @@ The `export s3` command starts exporting data and information on the server side
 {{ ydb-cli }} [connection options] export s3 [options]
 ```
 
+{% note warning %}
+
+The export feature is available only for objects of the following types:
+
+- [Directory](../../../../concepts/datamodel/dir.md)
+- [Row-oriented table](../../../../concepts/datamodel/table.md#row-oriented-tables)
+- [Secondary index](../../../../concepts/secondary_indexes.md)
+
+{% endnote %}
+
 {% include [conn_options_ref.md](../../commands/_includes/conn_options_ref.md) %}
 
 ## Command line parameters {#pars}

ydb/docs/ru/core/reference/ydb-cli/export-import/_includes/export-s3.md

@@ -6,6 +6,16 @@
 {{ ydb-cli }} [connection options] export s3 [options]
 ```
 
+{% note warning %}
+
+Выгрузка доступна только для объектов следующих типов:
+
+- [директория](../../../../concepts/datamodel/dir.md);
+- [строковая таблица](../../../../concepts/datamodel/table.md#row-oriented-tables);
+- [вторичный индекс](../../../../concepts/secondary_indexes.md).
+
+{% endnote %}
+
 {% include [conn_options_ref.md](../../commands/_includes/conn_options_ref.md) %}
 
 ## Параметры командной строки {#pars}