Create a release checklist/SOP

[BigLep]

It's awesome a release SOP has been started here: #384 (comment) 🎉

A few things. Can we:

1. Make it discoverable? - I think this is mostly just extracting it out of a specific release issue. Whether it become an issue that is cloned from, an issue template, or a markdown file that copy/paste from, it doesn't really matter.
2. Add a checklist component? - I like how the SOP provides explanatory information and rationale. The further improvement would be to make it easy for the person releasing to know where they are and show their status.

For reference, here are some other release templates:

• https://github.com/ipfs/go-ipfs/blob/master/docs/RELEASE_ISSUE_TEMPLATE.md
• https://github.com/libp2p/go-libp2p/blob/master/.github/ISSUE_TEMPLATE/release.md