Complete 26.3 parity acceptance and dual-version release workflow

README.md

@@ -25,6 +25,13 @@ See the [26.3 guide](ports/mc263/README.md) and
 [release notes](ports/mc263/RELEASE_NOTES_26.3.0.1.md).
 Keep the builds and their saves separate, and back up worlds before updating.
 
+Minecraft **26.3** is also supported through a separate **Java 25 / NeoForge
+26.3.0.99** release with a first-party Age backend. See the
+[26.3 guide](ports/mc263/README.md) and
+[parity review](docs/MC263_PARITY_REVIEW.md). Keep the game-version JARs and saves
+separate; 1.21.1 remains supported with its existing dependencies. The guide below
+describes 1.21.1 unless stated otherwise.
+
 ## Getting started
 
 1. Make an Ink Vial from two black dyes, a glass bottle, and a water bucket.