Clarify need for the migration_port Xen param
Clarify need for the migration_port Xen param

... depending on which toolstack is used.

Signed-off-by: Hrvoje Ribicic <be5828fca31f89218048bec4189e30a581aa65da@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

leshchevds/ganeti,leshchevds/ganeti,yiannist/ganeti,andir/ganeti,yiannist/ganeti,onponomarev/ganeti,yiannist/ganeti,andir/ganeti,andir/ganeti,bitemyapp/ganeti,mbakke/ganeti,mbakke/ganeti,grnet/snf-ganeti,mbakke/ganeti,ganeti/ganeti,grnet/snf-ganeti,onponomarev/ganeti,ganeti/ganeti,leshchevds/ganeti,bitemyapp/ganeti,ganeti/ganeti