Write documentation to build Protobuf Message for IOS to register a starname

[annatorok]

Guide for this document:
https://github.com/cosmostation/cosmostation-mobile

Goal:
To show what our partners need to do to build a send IOV Token transaction and serializing with Protobuf and give an example with a send transaction with Swift.

• a separate page is created on docs.iov.one for Mobile iOS (Swift)

[orkunkl]

Currently protool does not support swift. But there is an open pull request regarding that uber/prototool#502 and I put the issue in devs attention again. But this does not mean we can't generate protobuf for swift. There is another way I used but just too much verbose. I'll explain it in the docs