message: Reflect inspector API change in docs
diff: @@ -335,8 +335,8 @@ Specializing on the Data Format
  -------------------------------
  Much like ``is_loading`` allows client code to dispatch based on the mode of an
  -inspector, the constant ``has_human_readable_format`` allows client code to
  -dispatch based on the data format.
  +inspector, the member function ``has_human_readable_format()`` allows client
  +code to dispatch based on the data format.
  The canonical example for choosing a different data representation for
  human-readable input and output is the ``enum`` type. When generating data for
  @@ -372,7 +372,7 @@ an ``enum class`` otherwise.
  template <class Inspector>
  static bool apply_object(Inspector& f, weekday& x) {
  - if constexpr (Inspector::has_human_readable_format) {
  + if (f.has_human_readable_format()) {
  auto get = [&x] { return to_string(x); };
  auto set = [&x](std::string str) { return parse(str, x); };
  f.object(x).fields(f.field("value", get, set));
  @@ -383,7 +383,7 @@ an ``enum class`` otherwise.
  template <class Inspector>
  static bool apply_value(Inspector& f, weekday& x) {
  - if constexpr (Inspector::has_human_readable_format) {
  + if (f.has_human_readable_format()) {
  auto get = [&x] { return to_string(x); };
  auto set = [&x](std::string str) { return parse(str, x); };
  return inspect_value(f, get, set);
  