[MINOR] Update docs with newly added configuration values (apache#3877)

docs/source/user-guide/configs.md

@@ -40,6 +40,8 @@ Environment variables are read during `SessionConfig` initialisation so they mus
 | datafusion.execution.batch_size                 | UInt64  | 8192    | Default batch size while creating new batches, it's especially useful for buffer-in-memory batches since creating tiny batches would results in too much metadata memory consumption.                                                                                                                                                                         |
 | datafusion.execution.coalesce_batches           | Boolean | true    | When set to true, record batches will be examined between each operator and small batches will be coalesced into larger batches. This is helpful when there are highly selective filters or joins that could produce tiny output batches. The target batch size is determined by the configuration setting 'datafusion.execution.coalesce_target_batch_size'. |
 | datafusion.execution.coalesce_target_batch_size | UInt64  | 4096    | Target batch size when coalescing batches. Uses in conjunction with the configuration setting 'datafusion.execution.coalesce_batches'.                                                                                                                                                                                                                        |
+| datafusion.execution.time_zone                  | Utf8    | UTC     | The session time zone which some function require e.g. EXTRACT(HOUR from SOME_TIME) shift the underline datetime according to the time zone,                                                                                                                                                                                                                  |
+| then extract the hour                           |
 | datafusion.explain.logical_plan_only            | Boolean | false   | When set to true, the explain statement will only print logical plans.                                                                                                                                                                                                                                                                                        |
 | datafusion.explain.physical_plan_only           | Boolean | false   | When set to true, the explain statement will only print physical plans.                                                                                                                                                                                                                                                                                       |
 | datafusion.optimizer.filter_null_join_keys      | Boolean | false   | When set to true, the optimizer will insert filters before a join between a nullable and non-nullable column to filter out nulls on the nullable side. This filter can add additional overhead when the file format does not fully support predicate push down.                                                                                               |