Draft communication plan for announcement of deployment changes

[CBonade]

Issue Description

With changes this big, we'll need a thorough communication plan for getting these notices out clearly, widespread, and often. A few areas that will need to be planned out are:

• team of teams announcements
• slack announcements in #vfs-all-teams, #vfs-frontend, #platform-cop-frontend, #platform-tech-team-support and #change-announcements
• determine the future of deployment notifications in #status-vets-website
• messaging within CI for things like our 60 day warning, or a deployment that requires approval from platform.

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Tasks

• Draft TOT announcements
• Draft Slack announcements
• Draft Slack automated notifcations
• Draft CI notifications

Acceptance Criteria

• A complete, comprehensive communication strategy and language has been determined.

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