DOC: fix typo in Unix Socket commands
Konstantin Romanenko reported a typo in the HTML documentation. The typo is
already present in the raw text version : the "shutdown sessions" command
should be "shutdown sessions server".
diff --git a/doc/configuration.txt b/doc/configuration.txt
index d69bb11..5f1b1cd 100644
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -14114,7 +14114,7 @@
endless transfer is ongoing. Such terminated sessions are reported with a 'K'
flag in the logs.
-shutdown sessions <backend>/<server>
+shutdown sessions server <backend>/<server>
Immediately terminate all the sessions attached to the specified server. This
can be used to terminate long-running sessions after a server is put into
maintenance mode, for instance. Such terminated sessions are reported with a