Update hello_input_system.adoc

Fixed list continuation error.

src/docs/asciidoc/jme3/beginner/hello_input_system.adoc

@@ -139,7 +139,7 @@ Have a look at the code:
                                       new MouseButtonTrigger(MouseInput.BUTTON_LEFT));
 
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-+
+
 Now you need to register your trigger mappings.
 
 .  You register the pause action to the ActionListener, because it is an “on/off action.