docs(README): add v3.0 beta

[giladgd]

Description of change

Add a message about the v3.0.0 beta to README.md

Pull-Request Checklist

• [x] Code is up-to-date with the master branch
• [x] npm run format to apply eslint formatting
• [x] npm run test passes with this change
• [x] This pull request links relevant issues as Fixes #0000
• [ ] There are new or updated unit tests validating the change
• [x] Documentation has been updated to reflect this change
• [x] The new commits and pull request title follow conventions explained in pull request guidelines (PRs that do not follow this convention will not be merged)

[github-actions[bot]]

:tada: This PR is included in version 2.8.1 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release
• v2.8.1

Your semantic-release bot :package::rocket:

[github-actions[bot]]

:tada: This PR is included in version 3.0.0-beta.2 :tada:

The release is available on:

• npm package (@beta dist-tag)
• GitHub release
• v3.0.0-beta.2

Your semantic-release bot :package::rocket: