Fix list item formatting to match spec
Fix list item formatting to match spec

kkiernan/commonmark,thephpleague/commonmark,colinodell/commonmark,postalservice14/commonmark,kkiernan/commonmark,hason/commonmark,garethellis36/commonmark,thephpleague/commonmark,fesor/commonmark,fesor/commonmark,stof/commonmark,bcremer/commonmark,hason/commonmark,postalservice14/commonmark,garethellis36/commonmark