Add CONTRIBUTING.md

[mjpitz]

To better inform followers on how to contribute to this library, lets add a CONTRIBUTING.md

[hnarasaki]

@mjpitz Would it be ok if I add the CONTRIBUTING.md from the indeedeng/cluster-preset repo https://github.com/indeedeng/cluster-preset/blob/master/CONTRIBUTING.md to this one?

[mjpitz]

@hnarasaki : sounds good. I've been meaning to draft a default one for projects to use.

[hnarasaki]

Hi @mjpitz, I'd like to do this one. Would it be possible to add the label hacktoberfest-accepted to this issue? No problem if not, I can still help out with this.

One thing I noticed is I'm not able to assign this issue to myself. Is self-assigning something admins would consider enabling in this repo?

[mjpitz]

@DuaneOBrien as I'm no longer at Indeed and he's got some better knowledge about what does and doesn't qualify.