Publish some "Good GitHub Issue" guidance

[kaylareopelle]

From @austinlparker in the CNCF Slack:

heya — just a note so it doesn’t get lost somehow, but it would be swell if we could have some sort of generalized “good github issue” guidance around things like ‘if i make an issue as a result of another issue/discussion, i link the new issue to the old via a mention’ and ‘if my issue is something that can be closed by a PR, i make sure to reference the issue in the PR’

[svrnm]

This could become part of the contributor handbook in the community repo.

[svrnm]

We could leverage .github repo to provide some ISSUE_TEMPLATEs and PULL_REQUEST templates across all repositories