Update interface-definitions/system_flow-accounting.xml.in

Co-authored-by: Daniil Baturin <daniil@baturin.org>

Author: hedrok

interface-definitions/system_flow-accounting.xml.in

@@ -117,7 +117,7 @@
               </tagNode>
               <leafNode name="inactive-timeout">
                 <properties>
-                  <help>Export flow after it's inactive for this timeout in seconds</help>
+                  <help>Flow inactivity timeout</help>
                   <valueHelp>
                     <format>u32:0-2147483647</format>
                     <description>Timeout to export inactive flow, seconds</description>