[NFC][libc++] Fixes minor issues in the synopsis.

Author: mordante

libcxx/include/chrono

@@ -922,18 +922,18 @@ strong_ordering operator<=>(const time_zone_link& x, const time_zone_link& y);
 }  // chrono
 
 namespace std {
+  template<class Rep, class Period, class charT>
+    struct formatter<chrono::duration<Rep, Period>, charT>;                       // C++20
   template<class Duration, class charT>
     struct formatter<chrono::sys_time<Duration>, charT>;                          // C++20
   template<class Duration, class charT>
     struct formatter<chrono::utc_time<Duration>, charT>;                          // C++20
   template<class Duration, class charT>
     struct formatter<chrono::tai_time<Duration>, charT>;                          // C++20
   template<class Duration, class charT>
-    struct formatter<chrono::filetime<Duration>, charT>;                          // C++20
+    struct formatter<chrono::file_time<Duration>, charT>;                         // C++20
   template<class Duration, class charT>
     struct formatter<chrono::local_time<Duration>, charT>;                        // C++20
-  template<class Rep, class Period, class charT>
-    struct formatter<chrono::duration<Rep, Period>, charT>;                       // C++20
   template<class charT> struct formatter<chrono::day, charT>;                     // C++20
   template<class charT> struct formatter<chrono::month, charT>;                   // C++20
   template<class charT> struct formatter<chrono::year, charT>;                    // C++20