Some related information:

This is introduced in https://github.com/doitsujin/dxvk/commit/307f43ff1e85c29fc7927fb7e522def8da70e615
Another related commit to enable it for Bad Company 2: https://github.com/doitsujin/dxvk/commit/2c53459f4c013159d91dfc53c58dc980c59ff5b9

Some discussion about this: https://github.com/doitsujin/dxvk/pull/2094

There are plenty more configs that aren't documented in the example config.
It is, or at least was, intentional to not have everything in there because some of them are for very specific rare use cases that end users shouldn't have to think about. Though you could argue some such configs are already in the dxvk.conf so that reasoning isn't always applied consistently.