[KYUUBI #6938] [DOC] Refine monitoring docs

### Why are the changes needed?

The PR is needed to make monitoring docs more clear and aligned with [General Style](https://kyuubi.readthedocs.io/en/master/contributing/doc/style.html#general-style):
 - Used unordered list instead of ordered (similar to other menus)
 - Deleted empty `events.md` page
 - Pages renamed to shorter versions
 - Fixed `Trouble Shooting` typo

### How was this patch tested?
Tested by building documentation locally.

**Before changes**
<img width="1189" alt="image" src="https://github.com/user-attachments/assets/9cd8e55e-9bf3-4667-b7d0-0188a71402a8" />

**After changes**
<img width="1213" alt="image" src="https://github.com/user-attachments/assets/2f51f24e-d997-45b4-b335-af9142d6ee08" />

### Was this patch authored or co-authored using generative AI tooling?

No

Closes #6938 from dnskr/refine-monitoring-docs.

Closes #6938

7ac8dcb2c [dnskr] [DOC] Refine monitoring docs

Authored-by: dnskr <dnskrv88@gmail.com>
Signed-off-by: Cheng Pan <chengpan@apache.org>

docs/monitor/events.md

@@ -1,19 +0,0 @@
-<!--
-- Licensed to the Apache Software Foundation (ASF) under one or more
-- contributor license agreements.  See the NOTICE file distributed with
-- this work for additional information regarding copyright ownership.
-- The ASF licenses this file to You under the Apache License, Version 2.0
-- (the "License"); you may not use this file except in compliance with
-- the License.  You may obtain a copy of the License at
--
--   http://www.apache.org/licenses/LICENSE-2.0
--
-- Unless required by applicable law or agreed to in writing, software
-- distributed under the License is distributed on an "AS IS" BASIS,
-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-- See the License for the specific language governing permissions and
-- limitations under the License.
--->
-
-# Monitoring Kyuubi - Events System
-

docs/monitor/index.rst

@@ -20,9 +20,8 @@ In this section, you will learn how to monitor Kyuubi with logging, metrics etc.
 
 .. toctree::
     :maxdepth: 2
-    :numbered: 3
     :glob:
 
     logging
     metrics
-    trouble_shooting
+    troubleshooting

docs/monitor/logging.md

@@ -15,7 +15,7 @@
 - limitations under the License.
 -->
 
-# Monitoring Kyuubi - Logging System
+# Logging
 
 Kyuubi uses [Apache Log4j2](https://logging.apache.org/log4j/2.x/) for logging since version v1.5.0. For versions v1.4.1 and below, it uses [Apache Log4j](https://logging.apache.org).
 
@@ -310,9 +310,8 @@ You will both get the final results and the corresponding operation logs telling
 
 ## Further Readings
 
-- [Monitoring Kyuubi - Events System](events.md)
-- [Monitoring Kyuubi - Server Metrics](metrics.md)
-- [Trouble Shooting](trouble_shooting.md)
+- [Metrics](metrics.md)
+- [Troubleshooting](troubleshooting.md)
 - Spark Online Documentation
   - [Monitoring and Instrumentation](https://spark.apache.org/docs/latest/monitoring.html)
 

docs/monitor/metrics.md

@@ -15,7 +15,7 @@
 - limitations under the License.
 -->
 
-# Monitoring Kyuubi - Server Metrics
+# Metrics
 
 Kyuubi has a configurable metrics system based on the [Dropwizard Metrics Library](https://metrics.dropwizard.io/).
 This allows users to report Kyuubi metrics to a variety of `kyuubi.metrics.reporters`.

docs/monitor/troubleshooting.md

@@ -15,7 +15,7 @@
 - limitations under the License.
 -->
 
-# Trouble Shooting
+# Troubleshooting
 
 ## Common Issues