[spp] [PATCH 1/2] doc: Fix document error under spp_vf directory

[Ferruh Yigit]

On 5/9/2018 6:45 AM, x-fn-spp at sl.ntt-tx.co.jp wrote:
> From: Hideyuki-Yamashita <yamashita.hideyuki at po.ntt-tx.co.jp>
> 
> - Fix typo in build.rst
> - Fix typo and error in usecase1.rst
> 
> 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>

Series applied, thanks.