Use Github Issues for release description setting

[toolmantim]

It'd be great if you could have a running changelog in a Github issue, and then use it when creating the release… so it's created with a fully fleshed out description as soon as it's created, no manually editing after the fact.

I tested it manually using https://github.com/buildkite/agent/issues/322 and https://github.com/buildkite/agent/issues/32 by hitting "edit" and copy and pasting the issue description into the release description, then commenting on each issue to link to the release, and finally closing the issue.

Perhaps something like:

--link-issue "$VERSION Changelog"

And it'd just search for the first issue with that name.

[wolfeidau]

Yeah I would love it if you could just pass in a blob of text.