Add a CONTRIBUTING.md File

[DBNess]

Description
We have a great issue template, but it's hard to find as a new contributor. If we use GitHub's CONTRIBUTING.md format, users will get a reminder like this when they open a new issue.

Ask
Create a CONTRIBUTING.md file with a quicklink to an issue using the awesome template provided by @courte in #347

To Do

• Add a basic CONTRIBUTING.md file in the root directory of this project
• Write a URL that creates a new GitHub issue with body content from template [ISSUE TEMPLATE] - Please use this template for any new issues! #347
• Add a quicklink section to the CONTRIBUTING.md file linking to the URL above
• Profit 💵 💰

Additional Info
Here's a link to an example of an issue template link courtesty of @sloria & Center for Open Science: https://github.com/CenterForOpenScience/OSF.io/issues/new?body=Steps%0A-------%0A1.%20%0A%0AExpected%0A------------%0A%0AActual%0A--------%0A

[buck3000]

Just submitted a pull request for this issue.