Documentation: routing policy priority defaults to 0

[Marco Corte]

The "priority" in a "routing-policy" section seems to default to 0.

The documentation should at least clearly state this fact, since the behaviour is different from the one of the "ip rule add" command; in a configuration like the following one, both rules get a "priority" 0, causing some troubles.

    bond0.347:
      addresses:
      - 10.64.44.151/22
      dhcp4: false
      dhcp6: false
      id: 347
      link: bond0
      routes:
      - to: 10.64.44.0/22
        via: 0.0.0.0
        scope: link
        table: 347
      - to: 0.0.0.0/0
        via: 10.64.47.254
        table: 347
      routing-policy:
      - from: 10.64.44.0/22
        table: 347
    bond0.337:
      addresses:
      - 10.64.37.21/24
      dhcp4: false
      dhcp6: false
      id: 337
      link: bond0
      routes:
      - to: 10.64.37.0/24
        via: 0.0.0.0
        scope: link
        table: 337
      - to: 0.0.0.0/0
        via: 10.64.37.254
        table: 337
      routing-policy:
      - from: 10.64.37.0/24
        table: 337