P0323R12 std::expected

- Introduce "General" subclauses to avoid hanging paragraphs.
- Introduce "Returns: *this" to avoid duplication.

Author: jensmaurer

source/lib-intro.tex

@@ -2480,7 +2480,6 @@
 \item \indexlibraryzombie{uncaught_exception} \tcode{uncaught_exception},
 \item \indexlibraryzombie{undeclare_no_pointers} \tcode{undeclare_no_pointers},
 \item \indexlibraryzombie{undeclare_reachable} \tcode{undeclare_reachable},
-\item \indexlibraryzombie{unexpected} \tcode{unexpected},
 and
 \item \indexlibraryzombie{unexpected_handler} \tcode{unexpected_handler}.
 \end{itemize}

source/support.tex

@@ -610,6 +610,7 @@
   // \libheader{unordered_set}
 #define @\defnlibxname{cpp_lib_exchange_function}@                 201304L // also in \libheader{utility}
 #define @\defnlibxname{cpp_lib_execution}@                         201902L // also in \libheader{execution}
+#define @\defnlibxname{cpp_lib_expected}@                          202202L // also in \libheader{expected}
 #define @\defnlibxname{cpp_lib_filesystem}@                        201703L // also in \libheader{filesystem}
 #define @\defnlibxname{cpp_lib_format}@                            202110L // also in \libheader{format}
 #define @\defnlibxname{cpp_lib_gcd_lcm}@                           201606L // also in \libheader{numeric}