Update README.md

Author: andrewshab3

README.md

@@ -14,7 +14,7 @@ The Immutable SDK for Unity helps you integrate your game with Immutable Passpor
 
 # Documentation
 
-* [Immutable X](https://docs.immutable.com/docs/x/sdks/unity)
+* [Immutable X](https://docs.immutable.com/reference/unity/)
 * [Immutable zkEVM](https://docs.immutable.com/docs/zkEVM/sdks/unity)
 
 ## Sample Projects