[spp] [PATCH] docs: add how to specify default route to classifier_table

[Yasufumi Ogawa]

> From: Hideyuki <yamashita.hideyuki at po.ntt-tx.co.jp>
> 
> This patch adds how to specify default route to classifier_table.
> 
> Signed-off-by: Hideyuki Yamashita <yamashita.hideyuki at po.ntt-tx.co.jp>
> Signed-off-by: Naoki Takada <takada.naoki at lab.ntt.co.jp>
> ---
>   docs/guides/spp_vf/commands/secondary.rst | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
> 
> diff --git a/docs/guides/spp_vf/commands/secondary.rst b/docs/guides/spp_vf/commands/secondary.rst
> index 58ccec5..872c162 100644
> --- a/docs/guides/spp_vf/commands/secondary.rst
> +++ b/docs/guides/spp_vf/commands/secondary.rst
> @@ -215,6 +215,15 @@ This is an example to register an entry for port ``ring:0``.
>   
>       spp > sec 1;classifier_table add mac 52:54:00:01:00:01 ring:0
First, you also should update before this line. The word 'entry' is a little ambiguous. Here is my proposal.

From:
This is an example to register an entry for port ``ring:0``.

To:
This is an example to register MAC address ``52:54:00:01:00:01``
with resource ID ``ring:0``.

>   
> +The difference is this example uses ``default`` instead of ``52:54:00:01:00:01`` to forward packets to ``ring:0`` if packets does not match any of registered
> +MAC address.
Second, It is too long. It should be less than 80 chars per one line.

I do not understand what is 'the difference' because you do not mention about the another example at first. Do you think 
changing it like this one.

Here is another example in which using keyword ``default`` instead of ``52:54:00:01:00:01``.
``default`` is used for packets which are not matched any of registered MAC addresses.
In this case, all of not matched packets are sent to ``ring:0``.

> +specifies default route and if the received packet
> +does not match any MAC address, then forwarded to specified default destination.
It is no need anymore.

> +
> +.. code-block:: console
> +
> +    spp > sec 0;classifier_table add mac default ring:0
> +
>   Register an entry with a VLAN ID to classifier table.
>   
>   .. code-block:: console
> @@ -228,6 +237,14 @@ for port ``ring:0``.
>   
>       spp > sec 0;classifier_table add vlan 101 52:54:00:01:00:01 ring:0
It is almost similar to the first comment above.

>   
> +The difference is this example uses ``default`` instead of ``52:54:00:01:00:01`` to forward packets to ``ring:1`` if packets does not match any of registered MAC address for specified VLAN_ID.
And it is also similar to the second comment above.

Thanks for your contribution.
> +specifies default route of the specified vlan and if the received packet
> +does not match any MAC address, then forwarded to specified default destination.
> +
> +.. code-block:: console
> +
> +    spp > sec 0;classifier_table add vlan 101 default ring:1
> +
>   Delete an entry.
>   
>   .. code-block:: console
>