fix xref

docs/modules/tutorials/pages/beginner/hello_asset.adoc

@@ -115,7 +115,7 @@ MyGame/...
 
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-This is just a suggested best practice, and it's what you get by default when creating a new Java project in the jMokeyEngine xref:ROOT:sdk.adoc[SDK]. You can create an `assets` directory and technically name the subdirectories whatever you like.
+This is just a suggested best practice, and it's what you get by default when creating a new Java project in the jMokeyEngine xref:sdk:sdk.adoc[SDK]. You can create an `assets` directory and technically name the subdirectories whatever you like.
 
 IMPORTANT: When you build your project for distribution, there will be no `assets` directory. Instead, you will generate an `assets.jar` file, located in the `dist/lib` folder of your project that will contain the sub-folders of the `assets` directory and all the assets in those folders.