Modify rule S6229 Add example with locale (CPP-5045)

- Add an example with a local locale
- Add links to documentation
- Correct a few typos
- I did not add an independent example using the global locale but added a comment

rules/S6229/cfamily/rule.adoc

@@ -3,10 +3,10 @@
 The ``++chrono++`` library, introduced in {cpp}20, provides support for calendars, time zones, and i/o formatting and parsing operations on time-related objects. 
 
 
-``++chrono++`` is a better alternative to the C/POSIX functions that operate on ``++time_t++``, ``++tm++``, or ``++timespec++`` types. In comparison to C facilities, it provides a better integration with other components of the {cpp} standard library: (``++iostreams++`` and ``++format++``). Also, it supports compile-time computation and it is thread safe.
+``++chrono++`` is a better alternative to the C/POSIX functions that operate on ``++time_t++``, ``++tm++``, or ``++timespec++`` types. In comparison to C facilities, it provides better integration with other components of the {cpp} standard library (``++iostreams++`` and ``++format++``). Also, it supports compile-time computation and it is thread-safe.
 
 
-This rule raises an issue on any use of C/POSIX functions that can be replaced with one of the ``++std::chrono++`` components:
+This rule raises an issue C/POSIX functions that can be replaced with one of the ``++std::chrono++`` components:
 
 * querying for current time (``++time++``, ``++timespec_get++``, ``++clock_gettime++``)
 * date to time-point conversion (``++mktime++``, ``++gmtime++``, ``++localtime++``)
@@ -42,17 +42,24 @@ std::optional<int> yearOfTimePoint(std::chrono::system_clock::time_point tp) {
   return date->tm_year + 1900;
 }
 
-std::string toIsoString(std::chrono::system_clock::time_point tp) {
+std::string toString(std::chrono::system_clock::time_point tp) {
   std::time_t t = std::chrono::system_clock::to_time_t(tp);
   std::tm* date = std::gmtime(&t);  // Noncompliant
   if (!date)
     throw InvalidDate();
 
   std::string buffer(100, ' ');
-  std::size_t written = std::strftime(buffer.data(), buffer.size(), "%F", date);
+  std::size_t written = std::strftime(&buffer[0], buffer.size(), "%A %c", date);
   buffer.resize(written);
   return buffer;
 }
+
+std::string toFrenchString(std::chrono::system_clock::time_point tp) {
+  auto oldLocale = std::locale::global(std::locale("fr_FR.UTF-8"));
+  std::string result = toString(tp);
+  std::locale::global(oldLocale);
+  return result;
+}
 ----
 
 === Compliant solution
@@ -78,8 +85,19 @@ std::optional<std::chrono::year> yearOfTimePoint(std::chrono::system_clock::time
   return date.year();
 }
 
-std::string toIsoString(std::chrono::system_clock::time_point tp) {
-  return std::format("{:%F}", tp);
+std::string toString(std::chrono::system_clock::time_point tp) {
+  return std::format("{:%A %c}", tp); // Or "{:L%A %c}" if you want to use the global locale
+}
+
+std::string toFrenchString(std::chrono::system_clock::time_point tp) {
+  return std::format(std::locale("fr_FR.UTF-8"), "{:L%A %c}", tp);
 }
 ----
 
+== Resources
+
+=== Documentation
+
+* {cpp} reference - https://en.cppreference.com/w/cpp/chrono[Date and time utilities]
+* {cpp} reference - https://en.cppreference.com/w/cpp/chrono/system_clock/formatter#Format_specification[Formatting `std::chrono::sys_time`]
+