docs: add note to upgrade guide about yanked version (#17115)

Nomad 1.5.4 shipped with a logmon bug that we rolled out a fix for in Nomad
1.5.5. Unfortunately we can't yank the release but we should leave a note in the
upgrade guide telling users to avoid it.

website/content/docs/upgrade/upgrade-specific.mdx

@@ -13,6 +13,30 @@ upgrade. However, specific versions of Nomad may have more details provided for
 their upgrades as a result of new features or changed behavior. This page is
 used to document those details separately from the standard upgrade flow.
 
+
+## Nomad 1.5.5
+
+Nomad 1.5.5 fixed a bug where allocations that are rescheduled for jobs
+registered before the upgrade would no longer collect allocation logs. The
+`logs.enabled` field introduced in 1.5.4 is now deprecated and has been replaced
+by a `logs.disabled` field that defaults to false. The `logs.enabled` field value
+will be ignored in 1.5.5 and will be removed in Nomad 1.6.0.
+
+## Nomad 1.5.4
+
+Nomad 1.5.4 included a bug where allocations that are rescheduled for jobs
+registered before the upgrade would no longer collect allocation logs. The
+client will emit debug-level logs like the following:
+
+```
+client.alloc_runner.task_runner.task_hook: log collection is disabled by task
+```
+
+You should avoid this version of Nomad and instead install the latest version of
+Nomad 1.5. If you have already upgraded to Nomad 1.5.4, upgrading to Nomad 1.5.5
+will restore logging collection when clients are restarted as part of the
+upgrade process.
+
 ## Nomad 1.5.1
 
 #### Artifact Download Regression Fix