docs: clean topics section of ceph troubleshooting guide

The topics section  of the ceph common problems troubleshooting guide
contained many subsection entries for symptoms, investigation and
solution.

Apart from not having working links,
these subsection entries  don't add any real value:
They are well visible within the overarching section
and in the toc on the right side.

This change cleans the toc by removing these unnecessary subsection
entries.

This also reduces the number of nonexisting anchor messages
of make docs-build from 50 to 18.

Signed-off-by: Michael Adam <obnox@samba.org>

Author: obnoxxx

Documentation/Troubleshooting/ceph-common-issues.md

@@ -10,66 +10,24 @@ title: Ceph Common Issues
 
 - [Troubleshooting Techniques](#troubleshooting-techniques)
     - [Ceph Tools](#ceph-tools)
-        - [Tools in the Rook Toolbox](#tools-in-the-rook-toolbox)
-        - [Ceph Commands](#ceph-commands)
+    - [Tools in the Rook Toolbox](#tools-in-the-rook-toolbox)
+    - [Ceph Commands](#ceph-commands)
 - [Cluster failing to service requests](#cluster-failing-to-service-requests)
-    - [Symptoms](#symptoms)
-    - [Investigation](#investigation)
-    - [Solution](#solution)
 - [Monitors are the only pods running](#monitors-are-the-only-pods-running)
-    - [Symptoms](#symptoms-1)
-    - [Investigation](#investigation-1)
-        - [Operator fails to connect to the mon](#operator-fails-to-connect-to-the-mon)
-        - [Solution](#solution-1)
-        - [Failing mon pod](#failing-mon-pod)
-        - [Solution](#solution-2)
 - [PVCs stay in pending state](#pvcs-stay-in-pending-state)
-    - [Symptoms](#symptoms-2)
-    - [Investigation](#investigation-2)
-        - [Confirm if there are OSDs](#confirm-if-there-are-osds)
-        - [OSD Prepare Logs](#osd-prepare-logs)
-        - [CSI Driver](#csi-driver)
-        - [Operator unresponsiveness](#operator-unresponsiveness)
-    - [Solution](#solution-3)
 - [OSD pods are failing to start](#osd-pods-are-failing-to-start)
-    - [Symptoms](#symptoms-3)
-    - [Investigation](#investigation-3)
-    - [Solution](#solution-4)
 - [OSD pods are not created on my devices](#osd-pods-are-not-created-on-my-devices)
-    - [Symptoms](#symptoms-4)
-    - [Investigation](#investigation-4)
-    - [Solution](#solution-5)
 - [Node hangs after reboot](#node-hangs-after-reboot)
-    - [Symptoms](#symptoms-5)
-    - [Investigation](#investigation-5)
-    - [Solution](#solution-6)
 - [Using multiple shared filesystem (CephFS) is attempted on a kernel version older than 4.7](#using-multiple-shared-filesystem-cephfs-is-attempted-on-a-kernel-version-older-than-47)
-    - [Symptoms](#symptoms-6)
-    - [Solution](#solution-7)
 - [Set debug log level for all Ceph daemons](#set-debug-log-level-for-all-ceph-daemons)
 - [Activate log to file for a particular Ceph daemon](#activate-log-to-file-for-a-particular-ceph-daemon)
 - [A worker node using RBD devices hangs up](#a-worker-node-using-rbd-devices-hangs-up)
-    - [Symptoms](#symptoms-7)
-    - [Investigation](#investigation-6)
-    - [Solution](#solution-8)
 - [Too few PGs per OSD warning is shown](#too-few-pgs-per-osd-warning-is-shown)
-    - [Symptoms](#symptoms-8)
-    - [Solution](#solution-9)
 - [LVM metadata can be corrupted with OSD on LV-backed PVC](#lvm-metadata-can-be-corrupted-with-osd-on-lv-backed-pvc)
-    - [Symptoms](#symptoms-9)
-    - [Solution](#solution-10)
 - [OSD prepare job fails due to low aio-max-nr setting](#osd-prepare-job-fails-due-to-low-aio-max-nr-setting)
 - [Unexpected partitions created](#unexpected-partitions-created)
-    - [Symptoms](#symptoms-10)
-    - [Solution](#solution-11)
-        - [Recover from corruption (v1.6.0-v1.6.7)](#recover-from-corruption-v160-v167)
 - [Operator environment variables are ignored](#operator-environment-variables-are-ignored)
-    - [Symptoms](#symptoms-11)
-    - [Investigation](#investigation-7)
-    - [Solution](#solution-12)
 - [The cluster is in an unhealthy state or fails to configure when LimitNOFILE=infinity in containerd](#the-cluster-is-in-an-unhealthy-state-or-fails-to-configure-when-limitnofileinfinity-in-containerd)
-    - [Symptoms](#symptoms-12)
-    - [Solution](#solution-13)
 
 
 Many of these problem cases are hard to summarize down to a short phrase that adequately describes the problem. Each problem will start with a bulleted list of symptoms. Keep in mind that all symptoms may not apply depending on the configuration of Rook. If the majority of the symptoms are seen there is a fair chance you are experiencing that problem.
@@ -94,15 +52,15 @@ After you verify the basic health of the running pods, next you will want to run
 * Other artifacts:
     * The monitors that are expected to be in quorum: `kubectl -n <cluster-namespace> get configmap rook-ceph-mon-endpoints -o yaml | grep data`
 
-#### Tools in the Rook Toolbox
+### Tools in the Rook Toolbox
 
 The [rook-ceph-tools pod](ceph-toolbox.md) provides a simple environment to run Ceph tools. Once the pod is up and running, connect to the pod to execute Ceph commands to evaluate that current state of the cluster.
 
 ```console
 kubectl -n rook-ceph exec -it $(kubectl -n rook-ceph get pod -l "app=rook-ceph-tools" -o jsonpath='{.items[*].metadata.name}') -- bash
 ```
 
-#### Ceph Commands
+### Ceph Commands
 
 Here are some common commands to troubleshoot a Ceph cluster: