Fix section docker ps --size
Remove the extra item "Size"
@@ -57,7 +57,7 @@ The `docker ps --size` (or `-s`) command displays two different on-disk-sizes fo
```console
$ docker ps --size
-CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES SIZE SIZE
+CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES SIZE
e90b8831a4b8 nginx "/bin/bash -c 'mkdir " 11 weeks ago Up 4 hours my_nginx 35.58 kB (virtual 109.2 MB)
00c6131c5e30 telegraf:1.5 "/entrypoint.sh" 11 weeks ago Up 11 weeks my_telegraf 0 B (virtual 209.5 MB)
```
