release-instructions.md

How to do a release:

1. Update CHANGELOG.md with a new entry and new link at the bottom.
2. Find and replace in the codebase to update the version number. Make sure to get Cargo.toml and places in the changelog. Be careful not the screw up old links though!
3. Commit.
4. Tag the commit with the version number.
5. Make a PR and make sure the tag gets added.
6. Merge the PR
7. cargo publish --dry-run
8. cargo publish