[PATCH v1] ring: correct the comment and figure description

[Thomas Monjalon]

08/04/2022 14:40, Haiyue Wang:
> The index description isn't right, correct it as the Programmer's guide
> said.
> 
> Also correct the guide's figure description about 'Dequeue First Step'.
> 
> Signed-off-by: Haiyue Wang <haiyue.wang at intel.com>

There was no comment, I assume it is OK.
Applied, thanks.