fix internal xref

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

@@ -367,7 +367,7 @@ Now you use the CollisionShape to create a `CharacterControl` that represents th
 
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-Apart from step height and character size, the `CharacterControl` lets you configure jumping, falling, and gravity speeds. Adjust the values to fit your game situation. There are some important nuances when setting these variable that are explained in greater detail in the <<2-onaction,onAction()>> topic later.
+Apart from step height and character size, the `CharacterControl` lets you configure jumping, falling, and gravity speeds. Adjust the values to fit your game situation. There are some important nuances when setting these variable that are explained in greater detail in the <<2-onaction(),onAction()>> topic later.
 
 [source,java]
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