Fixes docker#5969 - spelling error fixed (docker#5970)

Author: erriapo

network/iptables.md

@@ -34,7 +34,7 @@ $ iptables -I DOCKER-USER -i ext_if ! -s 192.168.1.0/24 -j DROP
 ```
 
 Finally, you can specify a range of IP addresses to accept using `--src-range`
-(Remember to also add `-m iprange` wen using `--src-range` or `--dst-range`):
+(Remember to also add `-m iprange` when using `--src-range` or `--dst-range`):
 
 ```bash
 $ iptables -I DOCKER-USER -m iprange -i ext_if ! --src-range 192.168.1.1-192.168.1.3 -j DROP