Fixed transposed pairwise feature size in README, and noted that feature...

Fixed transposed pairwise feature size in README, and noted that feature dimensionality is not necessarily equal to number of labels.

README.md

@@ -154,7 +154,7 @@ Instead, you need to use the generic `addPairwiseEnergy` method like this:
 d = dcrf.DenseCRF(100, 3)  # npoints, nlabels
 
 feats = np.array(...)  # Get the pairwise features from somewhere.
-print(feats.shape)     # -> (100, 3)
+print(feats.shape)     # -> (5, 100) = (feature dimensionality, npoints)
 print(feats.dtype)     # -> dtype('float32')
 
 dcrf.addPairwiseEnergy(feats)