Add playbooks version section

[jpipkin1]

Purpose of this pull request

This pull request adds a section on playbook versioning.

Select the type of change

• [ ] Minor Changes - Typos, formatting, slight revisions
• [ ] Update Content - Revisions, updating sections
• [x] New Content - New features, sections, pages, tutorials
• [ ] Site and Tools - .clabot, version updates, maintenance, dependencies, new packages for the site (Docusaurus, Gatsby, React, etc.)

Ticket (if applicable)

DOCS-52