Updates for CI phase 3

[nghi-ly]

What are you changing in this pull request and why?

Update docs for the GA of CI phase 3:

• Create release notes
• Update the Troubleshooting section -- removed the old Temp PR schema limitations section and consolidated the generate_schema_name use case into Troubleshooting
• Update the How it works section -- updated the wording in the last paragraph to account for new changes

Checklist

• Review the Content style guide and About versioning so my content adheres to these guidelines.
• Needs review from product team

Adding new pages (delete if not applicable):

• Provide a unique filename for the new page

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Name	Status	Preview	Comments	Updated (UTC)
docs-getdbt-com	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Sep 20, 2023 4:27pm

[aaronraff]

This looks great! I've only requested one very small change to ensure that we are communicating the correct prefix that's required for temporary schema dropping.

[aaronraff]

Ah sorry, I found one more occurrence of the required schema prefix that should be updated. No need to re-request a review though, everything else looks great. Thanks for doing this!

[mirnawong1]

looks awesome! left some non blocking suggestions to help users as they read through these helpful docs. approved for you to merge @nghi-ly