docs: clean OSS and COS configuration tables (#3452)

## summary
fixed formatting issues in OSS and Tencent COS configuration
documentation

## changes
- fixed broken markdown table alignment in OSS section
- cleaned and standardized OSS configuration table
- separated Tencent COS into its own properly formatted section
- ensured all configuration keys remain unchanged
- improved readability of documentation

## testing
- pre-commit checks passed
- markdown linting passed
- documentation-only change (no code behavior impact)

Author: Sidra-009

mkdocs/docs/configuration.md

@@ -193,17 +193,32 @@ For the FileIO there are several configuration options available:
 
 PyIceberg uses [S3FileSystem](https://arrow.apache.org/docs/python/generated/pyarrow.fs.S3FileSystem.html) class to connect to OSS bucket as the service is [compatible with S3 SDK](https://www.alibabacloud.com/help/en/oss/developer-reference/use-amazon-s3-sdks-to-access-oss) as long as the endpoint is addressed with virtual hosted style.
 
-| Key                  | Example             | Description                                      |
-| -------------------- | ------------------- | ------------------------------------------------ |
-| s3.endpoint          | <https://s3.oss-your-bucket-region.aliyuncs.com/>      | Configure an endpoint of the OSS service for the FileIO to access. Be sure to use S3 compatible endpoint as given in the example. |
-| s3.access-key-id     | admin                      | Configure the static access key id used to access the FileIO.                                                                                                                                                                                             |
-| s3.secret-access-key | password                   | Configure the static secret access key used to access the FileIO.                                                                                                                                                                                         |
-| s3.session-token     | AQoDYXdzEJr...             | Configure the static session token used to access the FileIO.                                                                                                                                                                                             |
-| s3.force-virtual-addressing   | True                       | Whether to use virtual addressing of buckets. This is set to `True` by default as OSS can only be accessed with virtual hosted style address.                                                                                                                                                                                                        |
-| s3.anonymous                | True                       | Configure whether to use anonymous connection. If False (default), uses key/secret if configured or standard AWS configuration methods. |
+| Key                          | Example                                            | Description |
+| ---------------------------- | -------------------------------------------------- | ----------- |
+| s3.endpoint                  | <https://s3.oss-your-bucket-region.aliyuncs.com/>    | Configure an endpoint of the OSS service for the FileIO to access. Be sure to use S3 compatible endpoint as given in the example. |
+| s3.access-key-id             | admin                                              | Configure the static access key id used to access the FileIO. |
+| s3.secret-access-key         | password                                           | Configure the static secret access key used to access the FileIO. |
+| s3.session-token             | AQoDYXdzEJr...                                     | Configure the static session token used to access the FileIO. |
+| s3.force-virtual-addressing  | True                                               | Whether to use virtual addressing of buckets. This is set to `True` by default as OSS can only be accessed with virtual hosted style address. |
+| s3.anonymous                 | True                                               | Configure whether to use anonymous connection. If False (default), uses key/secret if configured or standard AWS configuration methods. |
 
 <!-- markdown-link-check-enable-->
 
+### Tencent Cloud Object Storage (COS)
+
+<!-- markdown-link-check-disable -->
+
+Tencent Cloud Object Storage (COS) is S3-compatible and can be used with PyIceberg using the existing S3FileIO / PyArrowFileIO implementation.
+
+| Key                  | Example                                  | Description |
+| -------------------- | ---------------------------------------- | ----------- |
+| s3.endpoint          | <https://cos.ap-guangzhou.myqcloud.com>    | Tencent COS S3-compatible endpoint |
+| s3.access-key-id     | admin                                    | Access key for COS |
+| s3.secret-access-key | password                                 | Secret key for COS |
+| s3.session-token     | AQoDYXdzEJr...                           | Optional session token |
+
+<!-- markdown-link-check-enable -->
+
 ### Hugging Face
 
 <!-- markdown-link-check-disable -->