wireguard: fix 'wireguard add peer' cli behavior
wireguard: fix 'wireguard add peer' cli behavior

- change 'port' to 'dst-port' to make the input self-explanatory
- add empty spaces to short help

Type: fix

Signed-off-by: Miroslav Miklus <fc62d731b57fd4f42cbd6fb8b555d3d536cf93e1@pantheon.tech>
Change-Id: I74c783e6e8629e61b1c100e9355d09cf5e35a750

FDio/vpp,FDio/vpp,chrisy/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,chrisy/vpp,chrisy/vpp,chrisy/vpp,FDio/vpp,FDio/vpp,FDio/vpp