Update xamarin-tutorial.md
Update xamarin-tutorial.md

jeffreylees/docs,Catografix/docs,yvonnewilson/docs,yvonnewilson/docs,Catografix/docs,Annyv2/docs,sandrinodimattia/docs,Catografix/docs,jeffreylees/docs,sandrinodimattia/docs,miparnisari/docs,Annyv2/docs,jeffreylees/docs,hamzawi06/docs,yvonnewilson/docs,auth0/docs,khorne3/docs,hamzawi06/docs,Annyv2/docs,khorne3/docs,sandrinodimattia/docs,khorne3/docs,auth0/docs,hamzawi06/docs,auth0/docs