Update README.md

[mosuem]

Update readme before archiving this repo.

After landing this, the repo can be archived.

---

• I’ve reviewed the contributor guide and applied the relevant portions to this PR.

Contribution guidelines:

• See our contributor guide for general expectations for PRs.
• Larger or significant changes should be discussed in an issue before creating a PR.
• Contributions to our repos should follow the Dart style guide and use dart format.
• Most changes should add an entry to the changelog and may need to rev the pubspec package version.
• Changes to packages require corresponding tests.

Note that many Dart repos have a weekly cadence for reviewing PRs - please allow for some latency before initial review feedback.

[coveralls]

coverage: 93.945%. remained the same
when pulling 0133397 on mosuem-patch-1
into 2f49644 on master.