xo-unit: refactor: ++ docs

docs/basis-unit-class.rst

@@ -10,14 +10,11 @@ Basis Unit
 A :code:`basis_unit` represents a unit belonging to a single native dimension.
 For example :code:`bu::meter` representing a distance of 1 meter.
 
+Class
+-----
+
 .. doxygenclass:: xo::qty::basis_unit
 
-Constants
----------
-
-.. doxygengroup:: basis-unit-mass-units
-.. doxygengroup:: basis-unit-distance-units
-
 Member Variables
 ----------------