Update version.md with unstable mod version

Added unstable mod version for Minecraft 26.1.x.

Author: KSSJW

docs/minecraft-java-edition/minecart-trains-fork/version.md

@@ -18,7 +18,7 @@ The latest development progress is displayed in a list.
 
 | Minecraft Version | Stable Mod Version                                    | Unstable Mod version                              |
 | :---------------- | :---------------------------------------------------- | :------------------------------------------------ |
-| 26.1.x            | <font color="skyblue">2.2.2+26.1.fabric</font>        | -                                                 |
+| 26.1.x            | <font color="skyblue">2.2.2+26.1.fabric</font>        | <font color="red">2.3.0-alpha.1+26.1</font>       |
 | 1.21.11           | <font color="limegreen">2.2.2+1.21.11.fabric</font>   | -                                                 |
 | 1.21.9 - 1.21.10  | <font color="limegreen">2.2.2+1.21.9.fabric</font>    | -                                                 |
 | 1.21.6 - 1.21.8   | <font color="limegreen">2.2.2+1.21.6</font>           | -                                                 |