Spelling fixes

Spelling errors found using github.com/lucasdemarchi/codespell
A tool to fix common misspellings.
This tool is licensed under GNU General Public License, version 2.

Change-Id: I99ddfba10e88b764554107ac6859502ef09c6234
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/extended/test_network_nping.robot b/extended/test_network_nping.robot
index de0a92e..9e067ac 100644
--- a/extended/test_network_nping.robot
+++ b/extended/test_network_nping.robot
@@ -47,7 +47,7 @@
     # ${port}- Network port.
 
     # This program expects host, port, type and number of packets to be sent
-    # and rate at which packets to be sent, should be given in commad line
+    # and rate at which packets to be sent, should be given in command line
     # by default it sends 100 TCP packets at 5 packets/second.
 
     ${cmd_buff}=  Run Keyword If  '${packet_type}' == 'icmp'