263 Feature Request: Scenario Template & Contribution Guide

[TeneBrae93]

Overview of Changes

• Created a scenario template with basic resources, output, and whitelisting to provide a starting place for CloudGoat contributors. I also provided comments explaining some of the main things to keep in mind.
• Updated the Contribution Guidelines on the main README to help people get started with contributing and linked them to the scenario template as a starting point

[TeneBrae93]

Good catch @andrew-aiken on the existing template (didn't even realize that) - and neither did the people I talked to at Rhino when we discussed this. It's also pretty light on details (doesn't show whitelisting a public resource like an EC2 which is a specific problem we ran into with a community-submitted scenario - the EC2 is public on the internet).

I added a new commit that just removes this old one entirely, and puts this new one in the scenario folder. I think this makes it easier for people to find; also by adding it to the main README's contribution guidelines, this one should be less hidden.

Finally, I noticed some things I missed (manifest.yml in particular), so I added that to the new scenario template.