docs: Fix template error in cli example

Signed-off-by: Max Morozov <max@morozov.page>
Signed-off-by: Max Morozov <gtmax.yo@gmail.com>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: maxmorozoff

docs/reference/commandline/inspect.md

@@ -107,7 +107,7 @@ $ docker inspect --format='{{.Config.Image}}' $INSTANCE_ID
 You can loop over arrays and maps in the results to produce simple text output:
 
 ```console
-$ docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}} {{$p}} -> {{(index $conf 0).HostPort}} {{end}}' $INSTANCE_ID
+$ docker inspect --format='{{range $p, $conf := .NetworkSettings.Ports}} {{$p}} -> {{with $conf}}{{(index . 0).HostPort}}{{else}}none{{end}} {{end}}' $INSTANCE_ID
 ```
 
 ### Find a specific port mapping