[Planning] Publish key information including release schedule

[Naomi-Wash]

Ensure the Release SIG determines and publishes a high-level release schedule to all SIGs, and adds the release to the calendar.

The Release SIG should work with all SIGs involved in the release to determine the schedule (e.g. sig/release, sig/testing, sit/docs-community, etc.).

This schedule should include, at minimum, the following dates:

1. Stabilization Brach Created - The date when the branch is created which eventually becomes the released code. This is the branch where testing occurs, and blocker / critical bug fixes are made.
2. Code Freeze - Beyond this date, any code entering the stabilization branch requires an exception.
3. Release Branch confirmed Stable - The date when the release branch is considered stable, as agreed on by the release manager and sigs.
4. Release - The date the release will take place.
   Example Issue: O3DE Release 23.5.0 (scheduled for May 3, 2023) - Key Information #133
   The Release SIG is responsible for communicating this schedule via. the #sig-release and #sig-all Discord channels. In addition, the Release SIG should post the release date on the calendar

Discord: #sig-release
Release SIG meetings: O3DE Calendar
Release SIG meeting agendas: GHI

[Naomi-Wash]

@Ulrick28 to finalize timeline by Friday, June 14