Auto merge of #12833 - kpreid:empty-enum-doc, r=Manishearth

Rephrase and expand `empty_enum` documentation.

* Remove incorrect claim that “wrappers around it are the conventional way to define an uninhabited type”.
* Discuss why one would use `!`, a newtype struct, or keep the enum.
* Add links to relevant documentation.

Before writing this change, I asked the community via [IRLO](https://internals.rust-lang.org/t/idiomatic-definition-of-uninhabited-never-newtypes/20877) and [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/Never.20type.20wrappers.20.2F.20defining.20uninhabited.20newtypes) for feedback. The broad consensus seemed to me to be that in a world where both `never_type` and `min_exhaustive_patterns` are stable and therefore available for general use, we _might_ want to `!` or newtypes of it — but it's certainly not “conventional” _yet._ Therefore, I've removed “conventional” and added a discussion of the pros and cons of different choices.

changelog: [`empty_enum`]: expanded documentation

0 files changed, 0 insertions, 0 deletions