[spp] Update structure of documentation

[Yasufumi Ogawa]

Hi all,

I have updated SPP documentation continuously for changes of command syntax or additional features or so. However, it is still 
remained to be required to update. SPP VF and spp-ctl are additional features and chapters in the documentation are separated 
from others to be changed easily because under active development. I think updates of spp-ctl and SPP VF have got decreased, so 
it is no need to be separated anymore.

I will move spp-ctl, SPP VF to each of subsections of 'Soft Patch Panel' and 'Setup Guide' properly. Please let me know if you 
have a plan to change docs of spp-ctl or SPP VF. I would like to wait for your update.

Thanks,
Yasufumi