Create documentation for GH actions

[RayRedGoose]

🚀 Feature Proposal

Create documentation for GH actions

Motivation

Actions can be confusing and there is no any description for them except some comments in yaml files.

Example

canvas-kit-actions repo has some documentation for its actions but it's good to have similar readme for canvas-kit

Acceptance Criteria

Docs for:

• [ ] Major release action
• [ ] Minor release action

[alanbsmith]

Docs should live in the Maintaining doc

[alanbsmith]

Request: Assign this work to someone who hasn't worked on GH Actions, please.