Fix typo in "ethernet lan switching" README (ARP section)

contents/ethernet_lan_switching/README.md

@@ -99,13 +99,21 @@ LANs use L2 layer frames.
 
 ### ARP Table
 
-Use `arp -a` to view the ARP table and show all ARP entries
-
-![](docs/arp_table.png.png)
-
 * `type static`: default entries
 * `type dynamic`: learned via ARP
 
+#### Windows / MacOS / Linux
+
+`arp -a` to view the ARP table and show all ARP entries
+
+![](docs/arp_table.png)
+
+#### Cisco IOS
+
+`show arp` to view the ARP table and show all ARP entries
+
+![](docs/ios_show_arp.png)
+
 ## Ping
 
 * network utility used to test reachability
@@ -121,10 +129,6 @@ In the above example the first of the 5 requests sent failed because of ARP.
 
 ![](docs/wireshark_ping.png)
 
-### Cisco IOS ARP
-
-![](docs/ios_show_arp.png)
-
 ## MAC Address Table
 
 To **show** the MAC Address table in CISCO devices use: