Rewrite of scaled mechanism documentation

doc/concepts/decor.rst

@@ -171,10 +171,13 @@ Take for example the built-in mechanism for passive leaky dynamics:
 
 4. Scaled mechanisms
 ~~~~~~~~~~~~~~~~~~~~~
-:ref:`Inhomogenous expressions  <labels-iexpr>` can be applied to mechanisms, to scale parameters on a cable cell, such that a parameter is inhomogenous along the cell.
-It is useful to have a quantity smoothly varying along the dendrite, for example with the distance from the root.
-These expressions yield a scaling factor, which is multiplied with the base value of the selected parameter. Internally, the value of each parameter is evaluated at mid-points of the cable partition of the cell.
-Currently, only :ref:`density mechanisms <cablecell-density-mechs>` are supported.
+Mechanism parameters are usually homogeneous along a cell. However, sometimes it is useful to scale parameters based on inhomogeneous properties.
+:ref:`Inhomogeneous expressions  <labels-iexpr>` provide a way to describe a desired scaling formula, which for example can include the cell radius or the distance to a given set of locations.
+The name is inspired by NeuroML's https://docs.neuroml.org/Userdocs/Schemas/Cells.html#schema-inhomogeneousparameter.
+Such an expression is evaluated along the cell and yields a scaling factor, which is multiplied with the base value of the selected parameter.
+Internally, this evaluation and scaling is done at mid-points of the cable partition of the cell.
+Currently, only parameters of :ref:`density mechanisms <cablecell-density-mechs>` can be scaled.
+
 
 .. code-block:: Python