Add default documentation to this repo

[MathewBiddle]

To encourage participation and/or simply document how this repository functions, I recommend adding a few standard documentation pieces to this repository.

For more information on each of the below items, see https://opensource.guide/starting-a-project/#launching-your-own-open-source-project

• license
• update readme with a little more context (answering some questions such as; What does this project do? Why is this project useful? How do I get started? Where can I get more help, if I need it?)
• contributing guidelines
• code of conduct

[MathewBiddle]

Added:

• https://github.com/ESIPFed/acdd/blob/main/LICENSE - CC0
• https://github.com/ESIPFed/acdd/blob/main/CODE_OF_CONDUCT.md - Used Contributor Covenant CoC.

[MathewBiddle]

should have probably done this in a PR. I'll do better next time.

[ksauby]

Whoops, I meant to do a PR also, but committed to the main repo, updating the README.