testnet deployment enables staging and production instructions

## Summary

One of the largest hold ups to EOSIO documentation was the lack of a testnet. The lack of which made progressing a user through the entire development experience require the user to deploy a testnet locally, which is not feasible for the majority of the audience.

Some recommended topics to cover:

- Deploying an app to testnet (likely a brand new top level section in "Getting Started")
- Understanding EOSIO Testnet's constraints.
- Virtual instructions for deploying to a production blockchain network powered by EOSIO.

### Motivation

Fully document the intended EOSIO development workflow.

## Steps to resolve this issue

- [x] Create a new section in "Getting Started"
- [ ] Use @iamveritas's documents prepared a year ago as a first drraft.
- [ ] Create several steps under the "Getting Started" section

### Draft the doc

- [ ] Write the doc, determine an appropriate location (likely somewhere in this repo's `/docs` directory)
- [ ] Set the `content_title` and `link_text` variables in the document's _frontmatter_ bloc

### Open a pull request

- [ ] Open a pull request with your work, providing a title that describes the problem being solved and including the words "Resolves #[this issue's number]" in the pull request body