DOC: management: Correct example reload command in the document

Current example is:

  `echo "reload" | socat /var/run/haproxy-master.sock`

it will cause socat error:

  `exactly 2 addresses required (there are 1); use option "-h" for help`

Correct working command is:

  `echo "reload" | socat /var/run/haproxy-master.sock stdin`
1 file changed