added info about fallback font family to programming guide #661
added info about fallback font family to programming guide #661

canyu9512/DTCoreText,gnr/DTCoreText,devontech/DTCoreText,niklassaers/DTCoreText,niklassaers/DTCoreText,DanGe42/DTCoreText,goodheart/DTCoreText,openresearch/DTCoreText,i-miss-you/DTCoreText,liulinjian/DTCoreText,qskycolor/DTCoreText,Akylas/DTCoreText,SanjoDeundiak/DTCoreText,shuoshi/DTCoreText,shuoshi/DTCoreText,davbeck/DTCoreText,z8927623/DTCoreText,DanGe42/DTCoreText,appunite/DTCoreText,appunite/DTCoreText,gsempe/DTCoreText,youprofit/DTCoreText,barz/DTCoreText,Cocoanetics/DTCoreText,barz/DTCoreText,1yvT0s/DTCoreText,Akylas/DTCoreText,artifacts/DTCoreText,w2592583/DTCoreText,artifacts/DTCoreText,programming086/DTCoreText,liuslevis/DTCoreText,pivotaltracker/DTCoreText,xiaoyanit/DTCoreText,z8927623/DTCoreText,jjamminjim/DTCoreText,qskycolor/DTCoreText,wangmb/DTCoreText,wlisac/DTCoreText,iwakevin/DTCoreText,sujeking/DTCoreText,rgregg/DTCoreText,devontech/DTCoreText,rain1988/DTCoreText,goodheart/DTCoreText,CoderJWYang/DTCoreText,canyu9512/DTCoreText,SanjoDeundiak/DTCoreText,yaoxiaoyong/DTCoreText,depl0y/DTCoreText,gank0326/CoreTextWithHTML,AmberWhiteSky/DTCoreText,artifacts/DTCoreText,bnickel/DTCoreText,rgregg/DTCoreText,davbeck/DTCoreText,Cocoanetics/DTCoreText,thusfresh/DTCoreText,i-miss-you/DTCoreText,wlisac/DTCoreText,cnbin/DTCoreText,jingchunYuan/DTCoreText,Cocoanetics/DTCoreText,bnickel/DTCoreText,jingchunYuan/DTCoreText,AmberWhiteSky/DTCoreText,rain1988/DTCoreText,sujeking/DTCoreText,artifacts/DTCoreText,1yvT0s/DTCoreText,depl0y/DTCoreText,cnbin/DTCoreText,gsempe/DTCoreText,Esdeath/DTCoreText,gank0326/CoreTextWithHTML,thusfresh/DTCoreText,liulinjian/DTCoreText,iwakevin/DTCoreText,wangmb/DTCoreText