chore: set up auto for versioning/release management

[hydrosquall]

Motivation

• Less time spent on managing package infra . See parent task https://github.com/orgs/vega/projects/8#card-69515101

Changes

• Replicate the setup in chore: set up auto for versioning/release management  vega-embed#749, + updates documentation

Testing

• CI should pass

Pre-merge checklist for a repo admin

• Create a branch called next from the current head of master https://github.com/vega/vega-datasets/tree/next
  • make next the base branch of this PR instead of master
  • make next the base branch for the whole repo
• Create a branch called stable from the latest tag v2.1.0 https://github.com/vega/vega-datasets/tree/stable
• Make a tagged release of the latest tag (exists, https://github.com/vega/vega-datasets/releases/tag/v2.1.0 )
• Create tags called skip-release and released in this repo (the first is used to tell auto not to release anything if this PR is released, the second is used to tag PRs that have been released).

📦 Published PR as canary version: 2.2.1--canary.312.32a9ed7.0

✨ Test out this PR locally via:

npm install vega-datasets@2.2.1--canary.312.32a9ed7.0
# or 
yarn add vega-datasets@2.2.1--canary.312.32a9ed7.0

[domoritz]

Please also update

The list of sources is in [SOURCES.md](https://github.com/vega/vega-datasets/blob/master/SOURCES.md).

in the Readme

[hydrosquall]

@domoritz great catch, just updated. 32a9ed7

Before we merge this, can you update next to be the default branch for this repository? (I would do it but don't have access yet).

[domoritz]

Done

[github-actions]

🚀 PR was released in v2.5.0-next.0 🚀