GitHub Issues Workflow for Chef

This RFC codifies the workflow of Chef maintainers while maintaining issues and contributions for Chef.

Special thanks to @btm / @lamont-granquist / @danielsdeleo / @mcquin / @adamedx / @jdmundrawala  who has helped put the first version come together.
Please clarify - is this:

- one year of waiting for response from the author
- one year with no comments from the author
- one year with no comments from anyone
- Chef ignores everything for one year and then closes it?

Additionally, one year seems very excessive. The probability that a patch will merge cleanly after one year is incredibly small. I would favor 6 months, adding an exception for issues that have existed prior to this RFC.

There also needs to document a process for how those issues are "retired". Is a label added? Is a special comment/flag added? Who does this? Is this part of regular triage or something a bot does? If this only happens once a year, it's likely to be forgotten and go by the wayside.