Fix typo in embodied question.

app.py

@@ -106,7 +106,7 @@ add a box to the scene at position [0, 0, 1], add a camera named "cam" at defaul
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 show the scene, step the scene once
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-what is the mean pixel value from the even frames from "cam".
+what is the mean pixel value from the frames from "cam".
 
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