(doc) Adds Ansible Guide for Nexus Upgrade

[JPRuskin]

Description Of Changes

Adds a brief Ansible playbook for upgrading Nexus

Motivation and Context

Other environments had guidance for upgrading Nexus, Ansible was missing it.

Testing

• [x] I have previewed these changes using the Docker Container or another method before submitting this pull request.

Change Types Made

• [ ] Minor documentation fix (typos etc.).
• [ ] Major documentation change (refactoring, reformatting or adding documentation to existing page).
• [x] New documentation page added.
• [ ] The change I have made should have a video added, and I have raised an issue for this.
  • Issue #

Change Checklist

• [ ] Requires a change to menu structure (top or left-hand side)/
• [ ] Menu structure has been updated