Update docs

doc/api.rst

@@ -29,8 +29,6 @@ to that of glibc's ``printf`` and better than the performance of IOStreams.
 
 .. doxygenfunction:: format(string_view, const Args&...)
 
-.. doxygenfunction:: operator""_format(const char *, std::size_t)
-
 .. _print:
 
 .. doxygenfunction:: print(string_view, const Args&...)
@@ -113,8 +111,17 @@ formatting of user-defined types that have overloaded ``operator<<``::
 
 .. doxygenfunction:: print(std::ostream&, string_view, const Args&...)
 
-Argument formatters
+Literal-based API
--------------------
+-----------------
+
+The following user-defined literals are defined in ``fmt/format.h``.
+
+.. doxygenfunction:: operator""_format(const char *, std::size_t)
+
+.. doxygenfunction:: operator""_a(const char *, std::size_t)
+
+Custom formatting of built-in types
+-----------------------------------
 
 It is possible to change the way arguments are formatted by providing a
 custom argument formatter class::
@@ -218,8 +225,6 @@ Utilities
 
 .. doxygenfunction:: fmt::arg(string_view, const T&)
 
-.. doxygenfunction:: operator""_a(const char *, std::size_t)
-
 .. doxygenclass:: fmt::basic_format_args
    :members:
 

include/fmt/core.h

@@ -1182,6 +1182,7 @@ std::wstring vformat(wstring_view format_str, wformat_args args);
 
   **Example**::
 
+    #include "fmt/core.h"
     std::string message = fmt::format("The answer is {}", 42);
   \endrst
 */