[json] add docs to the usage page
[json] add docs to the usage page

beealone/Silex,Xephi/Silex,SanderKnape/Silex,akucherevskiy/developex_test,GromNaN/Silex,romainneutron/Silex,cesarmarinhorj/Silex,cesarmarinhorj/Silex,mTorres/Silex,cgsmith/Silex,jdreesen/Silex,naderman/Silex,romainneutron/Silex,GromNaN/Silex,silexphp/Silex,akucherevskiy/developex_test,mathroc/Silex,JPry/Silex,Tobion/Silex,lokhman/Silex,lokhman/Silex,fhinkel/Silex,Incognito/silex-fork,lyrixx/Silex,JPry/Silex,lyrixx/Silex,Tobion/Silex,SanderKnape/Silex,peterkokot/Silex,fabpot/Silex,akucherevskiy/developex_test,stof/Silex,RayRutjes/Silex,CarsonF/Silex,Xephi/Silex,SpacePossum/Silex,arduanov/Silex,jdreesen/Silex,mathroc/Silex,stof/Silex,peterkokot/Silex,mTorres/Silex,GromNaN/Silex,plotek/Silex,mmauri04/Silex,tcx1000/Silex,CarsonF/Silex,plotek/Silex,lyrixx/Silex,naderman/Silex,gencer/Silex,Tobion/Silex,arduanov/Silex,stof/Silex,RayRutjes/Silex,peterkokot/Silex,romainneutron/Silex,naderman/Silex,beealone/Silex,Incognito/silex-fork,cgsmith/Silex,fabpot/Silex,SpacePossum/Silex,CarsonF/Silex,fhinkel/Silex,mmauri04/Silex,tcx1000/Silex