Flip pitch to `/.../` as the main syntax
Flip pitch to `/.../` as the main syntax

A quick pass to flip `/.../` out of the alternatives
and into the main syntax. Still needs a bunch of
work.

Also add some commentary on a regex with `]` as the
starting character.

apple/swift-experimental-string-processing,apple/swift-experimental-string-processing,apple/swift-experimental-string-processing