Document the hygiene behavior of syn::parse_str
diff --git a/src/lib.rs b/src/lib.rs
index 12e345d..77b0d23 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -610,6 +610,11 @@
 ///
 /// *This function is available if Syn is built with the `"parsing"` feature.*
 ///
+/// # Hygiene
+///
+/// Every span in the resulting syntax tree will be set to resolve at the macro
+/// call site.
+///
 /// # Examples
 ///
 /// ```rust