Fix a typo in the help string.
diff --git a/web/add_flow.py b/web/add_flow.py
index 6b9d5d0..eed75f9 100755
--- a/web/add_flow.py
+++ b/web/add_flow.py
@@ -491,7 +491,7 @@
usage_msg = usage_msg + " Flags:\n"
usage_msg = usage_msg + " -m [monitorname] Monitor and maintain the installed shortest path(s)\n"
usage_msg = usage_msg + " If 'monitorname' is specified and is set to 'ONOS'\n"
- usage_msg = usage_msg + " ((case insensitive), then the flow generation and\n"
+ usage_msg = usage_msg + " (case insensitive), then the flow generation and\n"
usage_msg = usage_msg + " maintanenance is done by ONOS itself.\n"
usage_msg = usage_msg + " Otherwise, it is done by this script.\n"
usage_msg = usage_msg + " -f <filename> Read the flow(s) to install from a file\n"