[SE-0311] Typo fixes (#1350)
[SE-0311] Typo fixes (#1350)

* [SE-0311] Typo fixes

- Update code examples using the old Task.local(_:)-Task.withLocal(_:body:) API.
- Correct some dashes
- Add dashes in compound adjectives
- Update the inheritance future direction to use the new API
- Slightly alter certain paragraphs to help readers parse them more easily

* Adjust code example’s indentation.

* Update table of contents.

* Type fixes.
abertelrud/swift-evolution,apple/swift-evolution,apple/swift-evolution,abertelrud/swift-evolution,natecook1000/swift-evolution,natecook1000/swift-evolution