man: explain journalctl --flush correctly

(cherry picked from commit 2a97b03b3b)

NEWS

@@ -7,6 +7,10 @@ CHANGES WITH 217:
           show log timestamps in the UTC timezone. journalctl now also
           accepts -n/--lines=all to disable line capping in a pager.
 
+        * journalctl gained a new switch, --flush, that flushes
+          logs from /run/log/journal to /var/log/journal if
+          persistent storage is enabled.
+
         * Services can notify the manager before they start a reload
           (by sending RELOADING=1) or shutdown (by sending
           STOPPING=1). This allows the manager to track and show the

man/journalctl.xml

@@ -883,9 +883,9 @@
 
                                 <listitem><para>Asks the Journal
                                 daemon to flush any log data stored in
-                                <filename>/run/systemd/log</filename>
+                                <filename>/run/log/journal</filename>
                                 into
-                                <filename>/var/systemd/log</filename>,
+                                <filename>/var/log/journal</filename>,
                                 if persistent storage is enabled. This
                                 call does not return until the
                                 operation is