Update docs/tutorial/kymographs.rst

Co-authored-by: Joep Vanlier <[email protected]>

docs/tutorial/kymographs.rst

@@ -167,7 +167,7 @@ If the background has to be subtracted, choose a region without binding events a
 .. image:: figures/kymographs/background.png
 
 Sum over the vertical axis (along the width of the binding event) to obtain the total photon counts over the selected regions.
-Since every pixel has an average background signal of `background_mean`, we need to sum the background over the same region to obtain the total background.
+Since every pixel has an average background signal of `background_mean`, we need to sum the background over the same region to obtain the total background::
 
     summed_photon_counts = np.sum(selection_green, axis=0)
     background_mean = np.mean(background.get_image(channel="green"))