docs(checkbox): checkbox attribute docs
docs(checkbox): checkbox attribute docs

manucorporat/ionic,alan-agius4/ionic,jhlee8804/ionic,TillaTheHun0/ionic,jhlee8804/ionic,janglednerves/ionic,TillaTheHun0/ionic,joshesp/ionic,jarrodkoch/ionic,dennybiasiolli/ionic,TillaTheHun0/ionic,jarrodkoch/ionic,joshesp/ionic,alan-agius4/ionic,AbraaoAlves/ionic,AbraaoAlves/ionic,cambronjay/ionic,jhlee8804/ionic,dennybiasiolli/ionic,janglednerves/ionic,TillaTheHun0/ionic,dennybiasiolli/ionic,janglednerves/ionic,manucorporat/ionic,alan-agius4/ionic,joshesp/ionic,alan-agius4/ionic,jarrodkoch/ionic,driftyco/ionic,driftyco/ionic,manucorporat/ionic,joshesp/ionic,janglednerves/ionic,alan-agius4/ionic,dennybiasiolli/ionic,alan-agius4/ionic,jarrodkoch/ionic,driftyco/ionic,jhlee8804/ionic,manucorporat/ionic,cambronjay/ionic,cambronjay/ionic,janglednerves/ionic,brianespinosa/ionic2-sass,driftyco/ionic,AbraaoAlves/ionic,jhlee8804/ionic,cambronjay/ionic,cambronjay/ionic,AbraaoAlves/ionic,AbraaoAlves/ionic,jarrodkoch/ionic,manucorporat/ionic,dennybiasiolli/ionic,driftyco/ionic