Developer Guide README, CONTRIBUTING, article templates for starport repo

[barriebyron]

I initially created these repo files for the https://github.com/cosmos/sdk-tutorials/ repo.

Now we have our Starport resources in the https://github.com/tendermint/starport/ repo.

Question 1: do we want a templates folder for the article templates? YES

• https://github.com/tendermint/starport/tree/develop/docs/contributing/templates

Question 2: do we want a developer-guide focus for readme and contributing? YES

Question 3: do we want a style guide for our developer guide? I can curate a style guide for Starport that will benefit all Tendermint and ecosystem
@barriebyron can do as part of issue #1650

[fadeev]

Perhaps, we can have docs/contributing for these files. We'll exclude this dir from the docs website sidebar.