Docs: small changes

docs/api/plugin-babylon.md

 
 The following diagram shows, in a simplified manner, the lifecycle of an AR experience. The rectangular blocks represent methods of your [ARDemo](#ardemo). Function [encantar](#encantar) starts the magic.
 
-![Lifecycle of an AR experience](/img/lifecycle-plugin.png)
+![Lifecycle of an AR experience](../img/lifecycle-plugin.png)
 
 !!! tip
 

docs/api/plugin-three.md

 
 The following diagram shows, in a simplified manner, the lifecycle of an AR experience. The rectangular blocks represent methods of your [ARDemo](#ardemo). Function [encantar](#encantar) starts the magic.
 
-![Lifecycle of an AR experience](/img/lifecycle-plugin.png)
+![Lifecycle of an AR experience](../img/lifecycle-plugin.png)
 
 <pre style="display:none">
 mermaid

docs/tutorial/next-steps.md

         );
     }
 
-    AR.Settings.powerPreference = 'low-power'; // OPTIONAL
+    AR.Settings.powerPreference = 'low-power'; // optional
 
     const tracker = AR.Tracker.Image();
     await tracker.database.add([{