Update README.md

README.md

@@ -22,9 +22,13 @@ healpix_fermi_intensity_skymap.cc
    The pixel solid angle (uniform = 4pi/number of pixels in HealPix) is used to convert units to intensity per sr.
   
    Units: 
+   
     counts:    counts in pixel in energy bands
+    
     exposure:  cm^2 s
+    
     intensity: photons cm^-2 sr⁻1 s⁻1  in energy bands
+    
 
    Requires HealPix v3.11  available from http://healpix.jpl.nasa.gov/