Generator: added some documentation for creating the states array.
Generator: added some documentation for creating the states array.

nickerso/libcellml,MichaelClerx/libcellml,nickerso/libcellml,hsorby/libcellml,hsorby/libcellml,cellml/libcellml,nickerso/libcellml,nickerso/libcellml,MichaelClerx/libcellml,MichaelClerx/libcellml,cellml/libcellml,cellml/libcellml,cellml/libcellml,hsorby/libcellml,hsorby/libcellml