update client secret doc
update client secret doc

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