v25.3 paths and alpha.1 (#19741)

* Script output

* Fix What's New Intro include to handle non-Prod state

* Add v25.3.0-alpha.1 release notes

* Update releases.yml and versions.csv

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Co-authored-by: ebembi-crdb <[email protected]>
Co-authored-by: katmayb <[email protected]>

Author: 3 people

src/current/_config_cockroachdb.yml

@@ -4,4 +4,4 @@ destination: _site/docs
 homepage_title: CockroachDB Docs
 versions:
   stable: v25.2
-  dev: v25.2
+  dev: v25.3