[Doc] Adding detail for data length field (backport StarRocks#51095) (StarRocks#51178)

Co-authored-by: Vikas Attiguppa <[email protected]>

Author: mergify[bot]

CONTRIBUTING.md

@@ -2,7 +2,7 @@
 
 StarRocks is built by an open and friendly community. We are dedicated to building a collaborative, inspiring, and exuberant open-source community for our members. Everyone is more than welcome to join our community to get help and to contribute to StarRocks.
 
-## Table of content
+## Table of contents
 
 - [How to contribute](#How-to-contribute)
 - [Contributing guideline](#Contributing-guideline)

docs/en/sql-reference/information_schema/tables.md

@@ -19,7 +19,7 @@ The following fields are provided in `tables`:
 | ROW_FORMAT      | Applies to a feature not available in StarRocks.             |
 | TABLE_ROWS      | Row count of the table.                                      |
 | AVG_ROW_LENGTH  | Average row length (size) of the table. It is equivalent to `DATA_LENGTH`/`TABLE_ROWS`. Unit: Byte. |
-| DATA_LENGTH     | Data length (size) of the table. Unit: Byte.                 |
+| DATA_LENGTH     | The data length of the table is determined by summing the data length of the table across all replicas. Unit: Byte.|
 | MAX_DATA_LENGTH | Applies to a feature not available in StarRocks.             |
 | INDEX_LENGTH    | Applies to a feature not available in StarRocks.             |
 | DATA_FREE       | Applies to a feature not available in StarRocks.             |