Open-sourcing Swift local refactoring functionality

Hey all,

We just open-sourced the local Swift refactoring functionality (PR: https://github.com/apple/swift/pull/11568\)!
And Xi wrote a blog post explaining how you can use the existing APIs to add your own local refactoring actions: Swift.org - Swift Local Refactoring

If you have any questions or comments, let us know!

-Argyrios