Explain how to specify boolean namelist options in the config.yaml file

[ccarouge]

For specifying a patch or a different set of science options, we need to list CABLE namelist options in benchcab's config.yaml file.

When listing namelist options with boolean values (true or false), they need to be specified using Python syntax (e.g. True) and not Fortran syntax (e.g. .true.). This needs to be specified in the documentation because, although it is logical considering how the config file is read and the values are used, it isn't immediately obvious.