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/diff.md

@@ -33,7 +33,7 @@ You can use the full or shortened container ID or the container name set using
 
 Inspect the changes to an `nginx` container:
 
-```bash
+```console
 $ docker diff 1fdfd1f54c1b
 
 C /dev