Add missing note from diffraction docs

This probably should be in here as well as the diff docs. Committing here so it doesn't get lost. 

RE #39471

Author: cailafinn

docs/source/release/v6.13.0/framework.rst

@@ -168,6 +168,8 @@ Python
 New features
 ############
 - ``Instrument.getFilename()`` and ``Instrument.setFilename()`` have been exposed to python.
+- A new method named ``getFittingParameter`` has been added to ``Mantid::Geometry::Component`` class and exposed to
+  python. This allows access to fitting parameters from components in an instrument definition file.
 
 Bugfixes
 ############