Update printer.h
Update printer.h

Setting classes in documentation instead of English words.
nickerso/libcellml,cellml/libcellml,nickerso/libcellml,nickerso/libcellml,hsorby/libcellml,hsorby/libcellml,nickerso/libcellml,hsorby/libcellml,MichaelClerx/libcellml,hsorby/libcellml,MichaelClerx/libcellml,MichaelClerx/libcellml,cellml/libcellml,cellml/libcellml,cellml/libcellml