Reformat the colorbar docstrings

Author: seisman

pygmt/base_plotting.py

@@ -225,10 +225,11 @@ def colorbar(self, **kwargs):
             Multiply all z-values in the CPT by the provided scale. By default
             the CPT is used as is.
         shading : str or list or bool
-            Add illumination effects. Passing a single numerical value sets the range
-            of intensities from -value to +value. If not specified, 1 is used.
-            Alternatively, set ``shading=[low, high]`` to specify an asymmetric
-            intensity range from *low* to *high*. The default is no illumination.
+            Add illumination effects. Passing a single numerical value sets the
+            range of intensities from -value to +value. If not specified, 1 is
+            used. Alternatively, set ``shading=[low, high]`` to specify an
+            asymmetric intensity range from *low* to *high*. The default is no
+            illumination.
         {V}
         {XY}
         {p}