[docs] rewrite usage POST example to not use Swiftmailer
[docs] rewrite usage POST example to not use Swiftmailer

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