It's in the quick reference guide (and on the Chroma website :) ).  I agree the detail can be cut down a bit, but I wanted to make sure that a wavelength-dependent diffraction limit was at least mentioned in the CHANGELOG.  Here's my edit:
  * `ChromaticObject.applyDilation()`, `.applyExpansion()`, and `.applyShift()`,
    can take function(s) of wavelength in nanometers as their argument(s), which
    can be used to create a variety of chromatic effects, for instance, a
    wavelength-dependent diffraction limit.