15.0: Back on schedule

15.0-ALPHA4 builds started on September 26h.

Approved by:	re (implicit)
Sponsored by:	https://www.patreon.com/cperciva

Author: cperciva

website/content/en/releases/15.0R/schedule.adoc

@@ -38,7 +38,7 @@ General discussions about the pending release and known issues should be sent to
 |ALPHA1 builds begin |5 September 2025 |6 September 2025 |First alpha test snapshot.
 |ALPHA2 builds begin |12 September 2025 |14 September 2025 |Second alpha test snapshot.
 |ALPHA3 builds begin |19 September 2025 |20 September 2025 |Third alpha test snapshot.
-|ALPHA4 builds begin |26 September 2025 |- |Fourth alpha test snapshot.
+|ALPHA4 builds begin |26 September 2025 |26 September 2025 |Fourth alpha test snapshot.
 |{localBranchReleng} branch |3 October 2025 |- |{localBranchReleng} branch created; future release engineering proceeds on this branch.
 |BETA1 builds begin |3 October 2025 |- |First beta test snapshot.
 |BETA2 builds begin |10 October 2025 |- |Second beta test snapshot.