Post for Go and Swift support

## PLEASE DO NOT MERGE

This is a first draft of the [post describing Go and Swift support](https://trello.com/c/2b7Z6pUX/15-new-languages-support-swift-and-go).

@neha3091 feel free to edit and comment. I've put a date on this for Thursday per the card, but can change if needed. I'll probably come back to this tomorrow (Wednesday) at some time also to proof again and make any changes I need that I missed.