docs/howto: update release steps with new automated steps
docs/howto: update release steps with new automated steps

There are now several pieces that can be used to automate some of the
release process. Update the documentation to reflect the newer,
easier-to-use steps. Additionally mention the need for signing the
SHA-256 hashes for integrity checking.

github/git-lfs,github/git-lfs,github/git-lfs