Updated the 'set_val_at_node' to 'set' under the Python diagnositc fields heading.
Updated the 'set_val_at_node' to 'set' under the Python diagnositc fields heading.


rjferrier/fluidity,jrper/fluidity,jjo31/ATHAM-Fluidity,rjferrier/fluidity,jjo31/ATHAM-Fluidity,rjferrier/fluidity,jrper/fluidity,jrper/fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,jrper/fluidity,iakovos-panourgias/fluidity,rjferrier/fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity,rjferrier/fluidity,jjo31/ATHAM-Fluidity