Add release notes for v1.0.0

Signed-off-by: Derek McGowan <derek@mcg.dev>

.mailmap

@@ -1,2 +1,4 @@
-Stephen J Day <stephen.day@docker.com> <stevvooe@users.noreply.github.com>
 Aaron Lehmann <aaronl@vitelus.com> <aaron.lehmann@docker.com>
+Derek McGowan <derek@mcg.dev> <derek@mcgstyle.net>
+Stephen J Day <stephen.day@docker.com> <stevvooe@users.noreply.github.com>
+Haibing Zhou <zhouhaibing089@gmail.com>

releases/README.md

@@ -0,0 +1,50 @@
+## go-digest release process
+
+1. Create release pull request with release notes and updated versions.
+
+   1. Compile release notes detailing features added since the last release and
+      add release template file to `releases/` directory. The template is defined
+      by containerd's release tool but refer to previous release files for style
+      and format help. Name the file using the version, for rc add an `-rc` suffix.
+      When moving from rc to final, the rc file may just be renamed and updated.
+      See [release-tool](https://github.com/containerd/release-tool)
+
+   2. Update the `.mailmap` files for commit authors which have multiple email addresses in the commit log.
+      If it is not clear which email or name the contributor might want used in the release notes, reach
+      out to the contributor for feedback. NOTE: real names should be used whenever possible. The file is
+      maintained by manually adding entries to the file.
+      - e.g. `Real Name <preferred@email.com> Other Name <other@email.com>`
+
+   3. Before opening the pull request, run the release tool using the new release notes.
+      Ensure the output matches what is expected, including contributors, change log,
+      dependencies, and visual elements such as spacing. If a contributor is duplicated,
+      use the emails outputted by the release tool to update the mailmap then re-run. The
+      goal of the release tool is that is generates release notes that need no
+      alterations after it is generated.
+
+2. Create tag
+
+   1. Choose tag for the next release, go-digest uses semantic versioning and
+      expects tags to be formatted as `vx.y.z[-rc.n]`.
+
+   2. Generate release notes (using a temp file may be helpful).
+      - e.g. `release-tool -l -d -n -t v1.0.0 ./releases/v1.0.0.toml > /tmp/v1.0.0-notes`
+
+   3. Create tag using the generated release notes.
+      - e.g. `git tag --cleanup=whitespace -s v1.0.0 -F /tmp/v1.0.0-notes`
+
+   4. Verify tag (e.g. `git show v1.0.0`), it may help to compare the new tag against previous.
+
+3. Push tag and Github release
+
+   1. Push the tag to `git@github.com:opencontainers/go-digest.git`.
+      NOTE: this will kick off CI building of the release binaries.
+
+   2. Create the Github release using the `Tag version` which was just pushed. Use the first
+      line outputted from the release tool as the `Release title` and the remainder of the
+      output for the description. No alteration of the release output should be needed.
+      Ensure `pre-release` is checked if an `-rc`.
+      NOTE: This should be done immediately after pushing the tag, otherwise CI may create the release
+      when the binaries are pushed.
+
+4. Promote on Slack, Twitter, mailing lists, etc

releases/v1.0.0.toml

@@ -0,0 +1,26 @@
+# commit to be tagged for new release
+commit = "HEAD"
+
+project_name = "go-digest"
+github_repo = "opencontainers/go-digest"
+
+pre_release = false
+
+preface = """\
+This is the first official release of the go-digest package. This package
+provides a simple toolkit for working with the digests used in the open
+containers ecosystem.
+
+This includes support for `sha256`, `sha384`, and `sha512` algorithms, with
+`sha256` being the most common and preferred for greatest compatibility across
+the ecosystem. Encoding ambiguity has been removed by only supporting lower
+case hex-encoded characters in the format for this release.
+
+The `digestset` package is provided to securely and unambiguously use
+shortened forms of the digest in environments where there is a full set
+of known digests."""
+
+# notable prs to include in the release notes, 1234 is the pr number
+[notes]
+
+[breaking]