docs: improve docstring and test comment

Author: yucongalicechen

Diff for: src/diffpy/utils/diffraction_objects.py

@@ -400,7 +400,7 @@ def scale_to(self, target_diff_object, q=None, tth=None, d=None, offset=None):
         """Returns a new diffraction object which is the current object but
         rescaled in y to the target.
 
-        By default, if `q`, `tth`, or `d` are not provided, scaling is based on the max q-value from each object.
+        By default, if `q`, `tth`, or `d` are not provided, scaling is based on the max intensity from each object.
         Otherwise, y-value in the target at the closest specified x-value will be used as the factor to scale to.
         The entire array is scaled by this factor so that one object places on top of the other at that point.
         If multiple values of `q`, `tth`, or `d` are provided, an error will be raised.

Diff for: tests/test_diffraction_objects.py

@@ -191,7 +191,7 @@ def test_init_invalid_xtype():
     "org_do_args, target_do_args, scale_inputs, expected",
     [
         # Test whether the original y-array is scaled as expected
-        (  # C1: none of q, tth, d, provided, expect to scale on the maximal x-arrays
+        (  # C1: none of q, tth, d, provided, expect to scale on the maximal intensity from each object
             {
                 "xarray": np.array([0.1, 0.2, 0.3]),
                 "yarray": np.array([1, 2, 3]),