docs: Add WebHDFS version compatibility details (#4024)

add webhdfs version compatibility

core/src/services/webhdfs/docs.md

@@ -23,12 +23,34 @@ This service can be used to:
 
 [Hdfs][crate::services::Hdfs] is powered by HDFS's native java client. Users need to set up the HDFS services correctly. But webhdfs can access from HTTP API and no extra setup needed.
 
+## WebHDFS Compatibility Guidelines
+
+### File Creation and Write
+
+For [File creation and write](https://hadoop.apache.org/docs/r3.1.3/hadoop-project-dist/hadoop-hdfs/WebHDFS.html#Create_and_Write_to_a_File) operations,
+OpenDAL WebHDFS is optimized for Hadoop Distributed File System (HDFS) versions 2.9 and later. 
+This involves two API calls in webhdfs, where the initial `put` call to the namenode is redirected to the datanode handling the file data.
+The optional `noredirect` flag can be set to prevent redirection. If used, the API response body contains the datanode URL, which is then utilized for the subsequent `put` call with the actual file data.
+OpenDAL automatically sets the `noredirect` flag with the first `put` call. This feature is supported starting from HDFS version 2.9.
+
+### Multi-Write Support
+
+OpenDAL WebHDFS supports multi-write operations by creating temporary files in the specified `atomic_write_dir`.
+The final concatenation of these temporary files occurs when the writer is closed.
+However, it's essential to be aware of HDFS concat restrictions for earlier versions,
+where the target file must not be empty, and its last block must be full. Due to these constraints, the concat operation might fail for HDFS 2.6.
+This issue, identified as [HDFS-6641](https://issues.apache.org/jira/browse/HDFS-6641), has been addressed in later versions of HDFS.
+
+In summary, OpenDAL WebHDFS is designed for optimal compatibility with HDFS, specifically versions 2.9 and later.
+
+
+
 ## Configurations
 
 - `root`: The root path of the WebHDFS service.
 - `endpoint`: The endpoint of the WebHDFS service.
 - `delegation`: The delegation token for WebHDFS.
-- `atomic_write_dir`: The tmp write dir of multi write for WebHDFS.
+- `atomic_write_dir`: The tmp write dir of multi write for WebHDFS.Needs to be configured for multi write support.
 
 Refer to [`Builder`]'s public API docs for more information.