Update README with rounding error warning
Update README with rounding error warning

2metres/neat,craftsmen/neat,Martskin/neat,craftsmen/neat,jessieay/neat,smithdamen/neat,thoughtbot/neat,setie/neat,bahtiyara/neat,craftsmen/neat,bgreg/neat,nickg33/neat,kennethormandy/straight-up,thoughtbot/neat,thoughtbot/neat,chriseppstein/neat,greyhwndz/neat