Add table of contents
Add table of contents

The reference document is quite large; a table of contents would help readers navigate and find topics. (TOC was generated via [DocToc](http://doctoc.herokuapp.com/))
andig/flot,k-joseph/flot,cipix2000/engineering-flot,stanislavdavid/flot,chaveiro/flot,stanislavdavid/flot,TrainingPeaks/flot,klarkc/flot,magora-suchkov/flot,resnick1223/flot,Sensirion/flot,octavianCraciun/engineering-flot,k-joseph/flot,lolifans/flot,gdseller/flot,fashionsun/flot,matong/flot,colinhunt/flot,sedran/flot,resnick1223/flot,chiu/flot,trask/flot,saike/flot,stanislavdavid/flot,soenter/flot,andig/flot,saike/flot,andig/flot,petrvacha/flot,k-joseph/flot,mlitwiniuk/flot,resnick1223/flot,saike/flot,soenter/flot,cipix2000/flot,MAMISHO/flot,mcanthony/flot,chiu/flot,chiu/flot,pepperdata/flot,chaveiro/flot,cipix2000/flot,flot/flot,kongx73/flot,mlitwiniuk/flot,chaveiro/flot,mlitwiniuk/flot,ni-kismet/engineering-flot