Update 1 -- async context inference
Update 1 -- async context inference

Re-working the async context inference section a little bit to highlight
the parallel between the top-level async context inference behavior and
the anonymous closure async context inference behavior.

natecook1000/swift-evolution,abertelrud/swift-evolution,natecook1000/swift-evolution,apple/swift-evolution,apple/swift-evolution,abertelrud/swift-evolution