Release Notes: Prod Manager reviews and approves

Before Release Notes are published for the GA release, they need to be carefully read by the Product Manager to verify that:
--all important new features are listed
--all Known Issues are listed
--any contributions or fixes made by the community are indicated as such
--all features that are in Tech Preview are marked as such
--the content reflects what we want to share with the community about this release.

The writer will send the Prod Manager an email with links to both the html version (for visual ease of reviewing) and to the source version. The prod manager and writer should determine the appropriate process for official sign-off (email, a Comment added to the GitHub PR, etc).