possible error in cmor documentation

[taylor13]

A possible problem with the documentation of the "units" argument of the cmor_variable and cmor_time_varying_grid_coordinate functions was raised: The documentation implies that if the unit is a (dimensionless) percentage, the user should pass units="percent", but I think it needs to pass "%". This is being checked and should be confirmed before making any change to the documentation.

[mauzey1]

@taylor13 "percent" and "%" are interchangeable for udunits2, however CMOR will still treat them as different units since they are different strings. Using "percent" shouldn't effect the unit conversion but the variable's history attribute would show that "percent" was converted to "%". All of the tables use "%" for percentage variables. Should CMOR enforce the use of "%" for percentages?