STYLE: clarify input requirements for extrusion models (#1181)
- changed the sectorCoeffs keyword to 'point' from 'axisPt' for more similarity with other dictionaries. Continue to accept 'axisPt' for compatibility.
- changed the sectorCoeffs keyword to 'point' from 'axisPt' for more similarity with other dictionaries. Continue to accept 'axisPt' for compatibility.