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 <geofflang@chromium.org>

doc/CodingStandard.md

@@ -69,10 +69,12 @@ underscore and use CamelCase.
 use CamelCase (chosen for consistency)
 * {DO} Constants: start with a **`k`** and use CamelCase
 * Namespaces: short names. use all lower case
-* Enum Names: use class enums when possible. The values should be uppercase with underscores or CamelCase.
+* {DEV} Enum Names: use strongly typed class enums when possible. Use CamelCase for class enum members. See [official docs][EnumsOfficial].
 * Macros: all uppercase with underscores
 * Exceptions to naming: use common sense!
 
+[EnumsOfficial]: https://google.github.io/styleguide/cppguide.html#Enumerator_Names
+
 ### [Comments](https://google.github.io/styleguide/cppguide.html#Comments)
 
 *   {DO} read and follow Google's recommendations.