PostgreSQL 18 Beta 1 release announcement draft

Hi,

Attached is a draft of the PostgreSQL 18 Beta 1 release announcement. 
The goal of this announcement is to introduce the new capabilities 
planned for PostgreSQL 18 and give users an idea of areas we'd like to 
see tested.

Please check for accuracy and if there are glaring omissions (happy to 
have the discussion on what to include in here, though note it's not 
possible to list everything in here). If a description is unclear or 
there are typos, I'm also happy to modify it; that said, for these 
suggestions I'm looking for recommendations that bring better clarity to 
a description vs. nitpicking over phrasing.

While I can make changes up until 2025-05-08 12:00 UTC, I won't be able 
to make anything substantive past 2025-05-08 02:00 UTC (especially 
because there's also the regular release this week!), so please have all 
feedback in by  2025-05-08 02:00 UTC.

Thanks - and thanks to everyone for their hard work on this release - 
I'm very excited for PostgreSQL 18!

Jonathan