move more detailed info about goal_expansion/2 to a later section
move more detailed info about goal_expansion/2 to a later section

mndrix/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,edechter/swipl-devel,koryonik/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,mndrix/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,edechter/swipl-devel,jn7163/swipl-devel,koryonik/swipl-devel,mndrix/swipl-devel,jn7163/swipl-devel,edechter/swipl-devel