Add upgrading docs for removed bottom-up client mode

refs #4799

diff --git a/doc/16-upgrading-icinga-2.md b/doc/16-upgrading-icinga-2.md
index c9ef6d088fd932d69e7ff105bbf40249ddcf4246..c5c85402d9976b39d6d23666579e02b9cca28f66 100644 (file)
--- a/doc/16-upgrading-icinga-2.md
+++ b/doc/16-upgrading-icinga-2.md
@@ -5,6 +5,8 @@ are scheme updates for the IDO database.
 
 ## Upgrading to v2.8 <a id="upgrading-to-2-8"></a>
 
+### Changed Certificate Paths <a id="upgrading-to-2-8-certificate-paths"></a>
+
 The default certificate path was changed from `/etc/icinga2/pki` to
 `/var/lib/icinga2/certs`.
 
@@ -15,6 +17,22 @@ The [setup CLI commands](06-distributed-monitoring.md#distributed-monitoring-set
 default [ApiListener configuration](06-distributed-monitoring.md#distributed-monitoring-apilistener)
 have been adjusted to these paths too.
 
+### Removed Bottom Up Client Mode <a id="upgrading-to-2-8-removed-bottom-up-client-mode"></a>
+
+This client mode was deprecated in 2.6 and was removed in 2.8.
+
+The node CLI command does not provide `list` or `update-config` anymore.
+
+The clients don't need to have a local `conf.d` directory included.
+The setup wizards for Linux and Windows attempt to disable this by default.
+
+Icinga 2 continues to run with the generated and imported configuration.
+You are advised to [migrate](https://github.com/Icinga/icinga2/issues/4798)
+any existing configuration to the "top down" mode with the help of the
+Icinga Director or config management tools such as Puppet, Ansible, etc.
+
+### Removed Classic UI Config Package <a id="upgrading-to-2-8-removed-classicui-config-package"></a>
+
 The config meta package `classicui-config` and the configuration files
 have been removed. You need to manually configure
 this legacy interface. Create a backup of the configuration