[func.wrap.ref.class] change deduction guide to match its detailed specifications

Author: JohelEGP

source/utilities.tex

@@ -14130,8 +14130,8 @@
     function_ref(F*) -> function_ref<F>;
   template<auto f>
     function_ref(nontype_t<f>) -> function_ref<@\seebelow@>;
-  template<auto f>
-    function_ref(nontype_t<f>, auto) -> function_ref<@\seebelow@>;
+  template<auto f, class T>
+    function_ref(nontype_t<f>, T&&) -> function_ref<@\seebelow@>;
 }
 \end{codeblock}