Fix markdown indentation level
@@ -280,6 +280,7 @@ Filtering with `reference` would give:
```bash
$ docker images --filter=reference='busy*:*libc'
+
REPOSITORY TAG IMAGE ID CREATED SIZE
busybox uclibc e02e811dd08f 5 weeks ago 1.09 MB
busybox glibc 21c16b6787c6 5 weeks ago 4.19 MB
