With all respect to your manual but he does do a good explanation on what the settings do, think very handy to know what you are adjusting, as what is perfect working onyour rig , does not always count on others. His explanation is maybe not that perfect but it is a good start for an game that did not have that big upgrade since his youtube movie from 30 dec 2018.That video is not what I'd personally follow by heart and it's definitely not CM specific, the guy spends 99% of the time covering basic AC graphics settings just presented in CM UI.
Dated too, from 2018, using old obsolete now gbwSuite.
You can also ignore advise on 91 fps limit for HMD, it will be synced at 90 no matter what you do, and AC will not be making extra frames in the presence of sync whether it's set in app or externally.