backticks for inline code

Author: JeremyPike

episodes/03-skimage-images.md

@@ -388,10 +388,10 @@ range 0-255 of an 8-bit pixel). The results should look like this:
 
 ![](fig/sudoku-gray.png){alt='Modified Su-Do-Ku puzzle'}
 
-*Hint: the 'cmap', 'vmin' and 'vmax' parameters of 'matplotlib.pyplot.imshow'
+*Hint: the `cmap`, `vmin` and `vmax` parameters of 'matplotlib.pyplot.imshow'
 will be needed to display the modified image as desired. See the [matplotlib
 documentation](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.imshow.html) 
-for more details on 'cmap', 'vmin' and 'vmax'.*
+for more details on `cmap`, `vmin` and `vmax`.*
 
 :::::::::::::::  solution