[Docs][Core] Update system logs doc for dashboard subprocess module (#50984)

Signed-off-by: Chi-Sheng Liu <chishengliu@chishengliu.com>

Author: MortalHappiness

doc/source/ray-observability/user-guides/configure-logging.md

@@ -47,6 +47,7 @@ System logs may include information about your applications. For example, ``runt
 ### System/component logs
 - ``dashboard.[log|err]``: A log file of a Ray Dashboard. ``.log`` files contain logs generated from the dashboard's logger. ``.err`` files contain stdout and stderr printed from the dashboard. They're usually empty except when the dashboard crashes unexpectedly.
 - ``dashboard_agent.log``: Every Ray node has one dashboard agent. This is a log file of the agent.
+- ``dashboard_[module_name].[log|err]``: The log files for the Ray Dashboard child processes, one per each module. ``.log`` files contain logs generated from the module's logger. ``.err`` files contain stdout and stderr printed from the module. They're usually empty except when the module crashes unexpectedly.
 - ``gcs_server.[out|err]``: The GCS server is a stateless server that manages Ray cluster metadata. It exists only in the head node.
 - ``io-worker-[worker_id]-[pid].[out|err]``: Ray creates IO workers to spill/restore objects to external storage by default from Ray 1.3+. This is a log file of IO workers.
 - ``log_monitor.[log|err]``: The log monitor is in charge of streaming logs to the driver. ``.log`` files contain logs generated from the log monitor's logger. ``.err`` files contain the stdout and stderr printed from the log monitor. They're usually empty except when the log monitor crashes unexpectedly.