chore(CONTRIBUTING): add steps for docs and demos
chore(CONTRIBUTING): add steps for docs and demos

references #6172

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