update trigger fork-rate

Author: vadv

mamonsu/plugins/system/linux/proc_stat.py

@@ -107,5 +107,5 @@ def triggers(self, template):
             'name': 'Process fork-rate to '
             'frequently on {HOSTNAME}',
             'expression': '{#TEMPLATE:system.processes[forkrate]'
-            '.last()}>' + str(self.ForkRate)
+            '.min(5m)}>' + str(self.ForkRate)
         })