Fix doc comment

Author: carbotaniuman

compiler/rustc_feature/src/unstable.rs

@@ -626,8 +626,9 @@ declare_features! (
     (unstable, type_changing_struct_update, "1.58.0", Some(86555)),
     /// Allows unnamed fields of struct and union type
     (incomplete, unnamed_fields, "1.74.0", Some(49804)),
-    /// Allows unsized fn parameters.
+    /// Allows unsafe attributes.
     (unstable, unsafe_attributes, "CURRENT_RUSTC_VERSION", Some(123757)),
+    /// Allows unsized fn parameters.
     (unstable, unsized_fn_params, "1.49.0", Some(48055)),
     /// Allows unsized rvalues at arguments and parameters.
     (incomplete, unsized_locals, "1.30.0", Some(48055)),