The old documentation for Maya 2016 has a page for ShaderFX:
https://help.autodesk.com/cloudhelp/2016/ENU/Maya-Tech-Docs/PyMel/generated/functions/pymel.core.oth...
There is no such page for Maya 2018.
Furthermore the ShaderFX documentation for Maya 2016 is very basic. It lacks detailed parameter explanations and usage examples. Currently it's a guessing game.
It would be great to see a documentation update.
Cheers!