Improve documentation on component.h using @code markup.
Improve documentation on component.h using @code markup.

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