Remove outdated doc about def_site
diff --git a/src/lib.rs b/src/lib.rs
index 274e60f..8453965 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -429,11 +429,7 @@
///
/// In this example it is important for the where-clause to be spanned with the
/// line/column information of the user's input type so that error messages are
-/// placed appropriately by the compiler. But it is also incredibly important
-/// that `Sync` resolves at the macro definition site and not the macro call
-/// site. If we resolve `Sync` at the same span that the user's type is going to
-/// be resolved, then they could bypass our check by defining their own trait
-/// named `Sync` that is implemented for their type.
+/// placed appropriately by the compiler.
#[macro_export]
macro_rules! quote_spanned {
($span:expr=> $($tt:tt)*) => {{