Update README.md

MP3/README.md

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     1.  **Vanishing Points [5 pts].** Estimate the three major orthogonal 
         vanishing points. Assume that the vertical vanishing point is for the 
         Y-direction, the vanishing point to the back of the ECE building is the 
-        Z-direction, and the horizontal vanishing point to the right is the 
+        Z-direction, and the horizontal vanishing point to the left is the 
         X-direction. Starter code provides an interface to mark out lines. Mark
         at least 3 lines in each orthogonal direction. We also provide data for 
         these lines in `Q3/data.pickle` in case you have trouble in using the