Update ES nested type mapping from JSON to VARIANT

Elasticsearch nested type should map to Doris VARIANT type for better
flexible schema handling. Added links to VARIANT documentation.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: dataroaring

docs/migration/elasticsearch-to-doris.md

@@ -25,7 +25,7 @@ This guide covers migrating data from Elasticsearch to Apache Doris. Doris can s
 
 2. **Index to Table Mapping**: Each Elasticsearch index typically maps to a Doris table.
 
-3. **Nested Documents**: Elasticsearch nested/object types map to Doris JSON type.
+3. **Nested Documents**: Elasticsearch nested types map to Doris [VARIANT](../data-operate/import/complex-types/variant.md) type for flexible schema handling.
 
 4. **Array Handling**: Elasticsearch arrays require explicit configuration in Doris.
 
@@ -48,7 +48,7 @@ This guide covers migrating data from Elasticsearch to Apache Doris. Doris can s
 | text | STRING | Consider inverted index in Doris |
 | date | DATE or DATETIME | See [Date Handling](#handling-date-types) |
 | ip | STRING | |
-| nested | JSON | |
+| nested | VARIANT | See [VARIANT type](../data-operate/import/complex-types/variant.md) for flexible schema |
 | object | JSON | |
 | flattened | JSON | Supported since Doris 3.1.4, 4.0.3 |
 | geo_point | STRING | Store as "lat,lon" string |

i18n/zh-CN/docusaurus-plugin-content-docs/current/migration/elasticsearch-to-doris.md

@@ -25,7 +25,7 @@
 
 2. **索引到表映射**：每个 Elasticsearch 索引通常映射到一个 Doris 表。
 
-3. **嵌套文档**：Elasticsearch nested/object 类型映射到 Doris JSON 类型。
+3. **嵌套文档**：Elasticsearch nested 类型映射到 Doris [VARIANT](../data-operate/import/complex-types/variant.md) 类型，支持灵活的 Schema 处理。
 
 4. **数组处理**：Elasticsearch 数组需要在 Doris 中显式配置。
 
@@ -48,7 +48,7 @@
 | text | STRING | 考虑在 Doris 中使用倒排索引 |
 | date | DATE 或 DATETIME | 参见[日期处理](#处理日期类型) |
 | ip | STRING | |
-| nested | JSON | |
+| nested | VARIANT | 参见 [VARIANT 类型](../data-operate/import/complex-types/variant.md)，支持灵活 Schema |
 | object | JSON | |
 | flattened | JSON | Doris 3.1.4、4.0.3 起支持 |
 | geo_point | STRING | 存储为 "lat,lon" 字符串 |