Update grant type guidance (#3702)
Update grant type guidance (#3702)

* start updating grant type guidance

* finish 1st version of new grant guidance

IdentityServer/IdentityServer4,MienDev/IdentityServer4,MienDev/IdentityServer4,IdentityServer/IdentityServer4,IdentityServer/IdentityServer4,MienDev/IdentityServer4,MienDev/IdentityServer4,IdentityServer/IdentityServer4