Specify that loadPriority also affects unloading order

User that want to also ensure that plugins are unloaded in a certain
order might want to know if loadPriority affects that as well, as its
not specified.

Ensure further clarity about the setting's behaviour by updating the
docs.

Release-Notes: skip
Change-Id: I24612d962fff23ca1d535492ace351befad5fed5

Documentation/config-gerrit.txt

diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index f48b90c..42edd90 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -5113,6 +5113,7 @@
 [[plugins.loadPriority]]plugins.loadPriority::
 +
 List of `pluginName`s required to have a specific loading order during Gerrit startup.
+Plugins will be unloaded in reverse order.
 +
 Each entry should contain a plugin name defined in the `MANIFEST.MF` under
 `Gerrit-PluginName` or a plugin JAR file name. During the Gerrit startup