docs: process: typo fix

In the second paragraph of section "Respond to review comments", there is
a spelling mistake: "aganst" should be "against".

Signed-off-by: Xujun Leng <lengxujun2007@126.com>
Link: https://lore.kernel.org/r/20230312071423.3042-1-lengxujun2007@126.com


Signed-off-by: Jonathan Corbet <corbet@lwn.net>