Tracking issue for `?` on either Option or Result in the same function

[carols10cents]

This section will need to be updated:

https://github.com/rust-lang-nursery/edition-guide/blame/1a7b200935c9a0c0964f928a92144e9e84e96d89/src/rust-2018/error-handling-and-panics/the-question-mark-operator-for-easier-error-handling.md#L117-L120

One current restriction is that you cannot use ? for both in the same function, as the return type needs to match the type you use ? on. In the future, this restriction will be lifted.

I'm not sure what the right Rust tracking issue to link to is. Maybe rust-lang/rust#31436 ?

[Nemo157]

std::option::NoneError which allows both links to rust-lang/rust#42327.

[ehuss]

Closing per #232, this section has been removed. Hopefully when those changes are stabilized it will trickle out to the right documentation.