Update docs on enum names.
Update docs on enum names.

Reflects the currenct approach for ANGLE enum naming.

Bug: angleproject:1944
Change-Id: I102ad8155d781888d96af06346afbce2e0e6cd59
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1779022
Reviewed-by: Geoff Lang <b6fc25fe0362055230985c05cbfa8adb741ccc0f@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle