Fixing typo (his --> its)

Signed-off-by: Brad Baker <brad@brad.fi>
(cherry picked from commit 172b2dc37e)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/run.md

@@ -348,7 +348,7 @@ explains in detail how to manipulate ports in Docker.
 
 Note that ports which are not bound to the host (i.e., `-p 80:80` instead of
 `-p 127.0.0.1:80:80`) will be accessible from the outside. This also applies if
-you configured UFW to block this specific port, as Docker manages his
+you configured UFW to block this specific port, as Docker manages its
 own iptables rules. [Read more](https://docs.docker.com/network/iptables/)
 
 ```console