fix(docs): broken link to preview

Signed-off-by: Gabriele Bartolini <gabriele.bartolini@enterprisedb.com>

Author: gbartolini

content/docs/preview.md

@@ -1,6 +1,6 @@
 ---
-release:  1.28.0-rc1
-location: /documentation/1.28
+release:  1.28.0-rc1 (preview)
+location: /documentation/preview
 release_date: 07 Nov 2025
 release_notes: https://github.com/cloudnative-pg/cloudnative-pg/releases/tag/v1.28.0-rc1
 ---