docs: use "console" code-hint for shell examples

This replaces the use of bash where suitable, to allow easier copy/pasting
of shell examples without copying the prompt or process output.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/plugin_push.md

@@ -26,7 +26,7 @@ Registry credentials are managed by [docker login](login.md).
 
 The following example shows how to push a sample `user/plugin`.
 
-```bash
+```console
 $ docker plugin ls
 
 ID             NAME                    DESCRIPTION                  ENABLED